Developer
Claude Certified Developer - Foundations
The whole certification as bullets and pictures, with the official exam keywords and the real situations behind each one.
Module 1
MSO Foundations
Orientation
- Four pillars before production code
- Tokens, context, models, prompting, first call
- Every lesson: hook, story, explore, quiz
- Quizzes from real deployment mistakes
Important to learn · exam keywords
APIcontext windows
Master the knife and measuring cup before cooking the big meal
How LLMs Behave
- Sampling: same input, different valid output
- Reads tokens, not words
- Context window: fixed token budget fills
- Roughly four characters per token
Important to learn · exam keywords
non-determinismsamplingtokenstoken budgetingmodel output
Context window fills like a glass, every token counts toward the brim
Models & Reasoning
- Two levers: model choice, reasoning mode
- Levers compose independently
- Smallest model, simplest reasoning passing eval
- Confusing levers: costliest production mistake
Important to learn · exam keywords
model output
Model is engine size, reasoning is the turbo boost
Prompting Modes
- Examples inside prompt, not training data
- Each example costs tokens, context budget
- Smallest reliable prompt beats more instructions
- Capable models often succeed zero-shot
Important to learn · exam keywords
code reviewmulti-shotzero-shotqualitytrade-offs
Show one finished plate instead of describing neat plating
Technical Substrate
- SDK and REST: same API, model
- Synchronous: wait for complete response
- Streaming: pieces via server-sent events
- Match request shape to user waiting
Important to learn · exam keywords
streamingSDKsAPIMessagesbatch API
Serve the whole plate at once, or courses as ready
Module Quiz & Recap
- Budget in tokens, not words
- Oversized input errors before generation
- History management: application's job
- Five foundations span whole module
Important to learn · exam keywords
token budgetingstreaming mode
A driving test checks all skills combined, not in isolation
Module 2
Prompting, Agents & Tool-use
Prompting Craft
- Diagnose failure mode before adding words
- Wrong shape needs output constraint
- Invented structure needs few-shot examples
- Constrained decoding compiles cached grammar, blocks prefilling
Important to learn · exam keywords
JSONoutput constraintsfew-shot examplesstructured outputcontext bloat
Tailor fixes the one loose seam, not the whole jacket
Extended Thinking
- Enable for multi-step reasoning only
- Off for classification, extraction lookups
- Tune depth via effort setting
- Return thinking blocks unchanged, signature verified
Important to learn · exam keywords
thinkingcode reviewextended thinkingadaptive thinkingmulti-step tasks
Staring longer helps a cryptic clue, wastes a known word
Tool-use & Schema
- Description drives selection: when, when not
- Every tool_use answered by matching tool_result
- Set disable_parallel_tool_use for sequential calls
- Hosted MCP connector serves remote servers only
Important to learn · exam keywords
toolsschema designtool usestdioMCP tools
Labelled toolbox says wrench turns bolts, not screws
Streaming
- Turn usable only after message_stop
- Discard partial interrupted turn, retry
- Parse tool_use JSON at content_block_stop
- Read stop_reason from message_delta
Important to learn · exam keywords
JSON
Parcel ready only after belt stops dropping pieces
Context Management
- Start Sonnet, move only on eval
- Count_tokens before send, budget proactively
- Pruning, compaction, clearing, subagents each lose something
- Cache stable prefix via cache_control ephemeral
Important to learn · exam keywords
content boundariesprompt versioningversion controlHaikuOpus
Backpacker weighs each item before the trailhead
Building Agents
- Enumerable steps: workflow, else agent
- Three wiring paths share one loop
- Human approval where actions irreversible
- Managed Agents not ZDR or HIPAA eligible
Important to learn · exam keywords
MessagesmaintainMessages API data access patternsfast modeClaude Agent SDK
Recipe follows steps; cook improvises an unknown pantry
Memory & State
- Choose memory scope during design
- Four scopes trade persistence against cost
- Skill loads on-demand matching SKILL.md description
- Subagent inherits permissions, not loaded Skills
Important to learn · exam keywords
prompt versioningmemorycontext bloatAgent Memory
Worker: pocket note, cabinet, summary, or blank slate
Cumulative Debug Task
- One bug per layer: schema, streaming, context, memory
- Streaming bug causes lone tool_result
- Commit stream after message_stop, thinking intact
- Long memory: external summary, not in-context
Important to learn · exam keywords
content boundariestool descriptions
Downstairs leak traced to the cracked upstairs pipe
Images, PDFs & Batch
- Visual tokens: ceil(width/28) times ceil(height/28)
- Send inline base64, URL, or Files API
- PDF needs document block, application/pdf
- Batch API: one job, not loop
Important to learn · exam keywords
batch APIMessage Batches API
Measure each box before packing the moving van
Module Quiz & Recap
- Drifting format signals missing system prompt
- Stripping thinking blocks breaks carry-back rule
- Eight takeaways span the full toolkit
Important to learn · exam keywords
tool-use loopscontext drift
Final driving test proves every skill holds together
Module 3
Claude Code, MCP & Integration
Orientation
- Local convenience becomes production failure
- Module teaches decisions around working integration
- Not re-teaching the agent loop
- Make configurable, shareable, safe
Important to learn · exam keywords
Claude Codeintegration
A recipe that flops in a friend's kitchen without assumptions written down
Permission Modes
- Agent loop plus permission gate
- Six modes trade speed for oversight
- Deny rule always beats allow rule
- Gate by worst unchecked outcome
Important to learn · exam keywords
settings.jsonsafety controls
Different keys for intern, colleague, robot by unsupervised damage
Durable Context
- CLAUDE.md loads every session unconditionally
- Growing CLAUDE.md dilutes rules that matter
- Rules files scope via paths glob
- Hooks fire every time, Explore skips CLAUDE.md
Important to learn · exam keywords
CLAUDE.mdfast modesubagentshooksbuilt-in Tools
Fridge rule greets everyone, cupboard note applies only there
Plugins & Skills
- Skill is portable SKILL.md, front matter matches
- Plugin bundles skills, hooks, MCP servers
- Plugin commands namespaced against collisions
- Hard-coded absolute paths break for others
Important to learn · exam keywords
Claude Agent SDKSkillsMCP server authoringcustom Toolsserver-side tools
Flat-pack shelf fails if a part stayed in designer's garage
MCP Server
- MCP separates tools into reusable server
- stdio local subprocess, HTTP recommended remote
- Prompt caching reuses stable prefix cheaply
- Inline .mcp.json key enters history forever
Important to learn · exam keywords
cachingprompt cachingstdioMCP promptsMCP resources
Shared wall outlet, but credential stays in separate env var
Enterprise & Recap
- Production answers identity, secrets, data residency
- OAuth remote, API key service, file-system local
- Staging-only config step fails in production
- Managed settings lock config, PostToolUse hook audits
Important to learn · exam keywords
plugin dependenciesapproval patternssecretsauthenticationaccess approval
Home dish must pass restaurant inspection and locked licence
Cumulative Integration
- Three bugs across configuration, packaging, auth layers
- Shortcut becomes production risk per layer
- Prefer safe portable over merely quick
- Fix mode, path, and inline token
Important to learn · exam keywords
MCP promptsMCP server authoringauthorizationcontent policy
Proofreading catches crossed word, scribble, margin password
Module 4
Production Engineering, Evals & Security
Orientation
- Fix four decisions in markdown first
- Success criteria, failure handling, budget, trust boundary
- Every layer built on those decisions
- Production failures are unmade decisions, not bugs
Important to learn
The Design Document Comes First
Before a road trip, agree on destination, driver, fuel budget, off-limits roads
Evals & Judges
- Eval defines done: cases, expected, grade
- Write eval before feature
- Match grading to output shape
- Calibrate judge against human-labeled cases
- Coverage beats perfection, span hard inputs
Important to learn
Most People Skip CalibrationThe Demo That Passed, The Edge Case That Did NotSingle correct label/value · Structured/code output · Open-ended quality
A thermometer checked against a reference gives a reading you can trust
Testing & Tracing
- Four levels: unit, functional, integration, end-to-end
- Integration test drives handoff with real data
- Trace localizes which step failed
- Classification router earns cost on mixed traffic
Important to learn · exam keywords
breaking behavior changescontext isolationfunction calling
Two plumbers pass their own tests, yet the joint between them leaks
Error Handling
- Retriable versus terminal: retry only retriable
- 429, 529, 500-504 retriable; 400-404 terminal
- Honor retry-after, else capped exponential backoff
- Check SDK retries, avoid double loops
- Return tool failures with is_error true
Important to learn · exam keywords
error handling
A shop closed for lunch clears with time; a wrong address never does
Cost & Orchestration
- Sonnet default, Opus or Haiku when measured
- Instrument tokens, latency, error rate upfront
- Message Batches API cheaper for async work
- Multi-agent costs roughly 15x tokens
- Set reliability floor first, tune cost above
Important to learn · exam keywords
cost modelingHaikuOpusSonnet
Hiring five researchers pays off only when work truly splits apart
Security & Recap
- Injection: one token stream, no boundary
- Real boundary is allowed actions, not text
- Least privilege scopes identity, explicit denies
- PreToolUse hook enforces and logs before action
Important to learn · exam keywords
prompt injectionguardrail layeringjailbreak defensesafety controls
A shouting stranger is harmless if every valuable stays locked away
Module 5
Accelerators & IP Contribution
Orientation
- Working build not yet finished
- Reusable, deployable, defensible decisions outweigh code
- Customer cloud, compliance, review drive choices
Important to learn · exam keywords
model version pinning
A meal tasting great in your kitchen a stranger cannot reproduce
Accelerators
- Accelerator starts engagement from working foundation
- Customer-specific values become documented config parameters
- Templates, MCP packages, eval suites packaged differently
- Bundle audit log for security review
Important to learn · exam keywords
credentialsfailure modes
Furniture kit: labelled parts, instructions, slots for your own screws
Contribution & Lifecycle
- Match contribution to documented channel
- Licensing, attribution clear before technical review
- Functional requirement checkable, becomes eval line
- Infrastructure constraints: latency, scale, residency, identity
Important to learn · exam keywords
infrastructure requirementsbusiness requirementsfunctional requirements
Chef confirms ownership and credits sources before shared cookbook
Deployment
- Platform shaped by customer existing cloud
- Residency answered by platform, not code
- Pin full model ID snapshot
- Gate promotion on eval against baseline
Important to learn · exam keywords
model version pinningversion controldeployment
Pick restaurant near home; pin the exact dish snapshot
Platform Comparison
- Measure latency from customer actual region
- Certified customer unlikely to re-certify
- Total cost includes egress, integration
- Pass-or-fail compliance determines placement alone
Important to learn · exam keywords
functional requirementscostlatencytrade-offs
Judge school by district admission, not glossy brochure
Boundaries & Capstone
- Contained as most privileged seam
- Trust boundary where data moves
- Fetched content untrusted; trust never carries
- Scope least privilege; confirm ZDR, BAA
Important to learn · exam keywords
instruction placementleast privilegeuntrusted inputidentity validation
House only as secure as its least-locked door