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aws-lambda-durable-functions

Builds resilient, long-running, multi-step applications with AWS Lambda durable functions with automatic state persistence, retry logic, and orchestration for long-running executions. Covers the critical replay model, step operations, wait/callback patterns, error handling with saga pattern, testing with LocalDurableTestRunner. Triggers on phrases like lambda durable functions, durable execution, workflow orchestration, state machines, retry/checkpoint patterns, long-running stateful Lambda functions, saga pattern, human-in-the-loop callbacks, reliable serverless applications, context.step, context.wait, context.invoke, context.runInChildContext, withDurableExecution, DurableContext, UnrecoverableInvocationError, durable-execution-sdk, qualified ARN invocation, and durable handler replay.

71

Quality

87%

Does it follow best practices?

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SecuritybySnyk

Low

Low-risk findings worth noting

SKILL.md
Quality
Evals
Security

Quality

Content

78%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A well-structured overview skill: tight, domain-specific body content with executable TypeScript/Python/bash examples, explicit review checklists, and an exemplary topic-to-file reference map backed by real bundle files. The main deductions are the near-duplicate restatement of the critical rules in Validation Guidelines and a couple of small completeness gaps in the Python examples.

Suggestions

Deduplicate the Validation Guidelines against Critical Rules: replace the four repeated items with a single pointer like "Validate against rules 3–6 above before committing" and keep only the test-specific checklist inline.

Close the Python example gaps: show the `Duration` import in the wait snippet and add a one-line `@durable_step` decorator example to match the TypeScript coverage.

State the entry-point workflow explicitly (e.g. "New durable function: follow getting-started.md steps 1–4, then validate with the checklist below") so the build sequence is visible in the body, not only in the reference file.

DimensionReasoningScore

Conciseness

The body is lean and skill-specific with no padding or explanation of concepts Claude already knows, but the "Validation Guidelines" section repeats four of the six "Critical Rules" nearly verbatim (non-deterministic code outside steps, nested durable operations, closure mutations, side effects outside steps). This fits the score-4 anchor (efficient with minor instances that could be trimmed) rather than score 5, where every token earns its place with no duplicated content.

4 / 5

Actionability

The body provides copy-paste-ready TypeScript and Python handler patterns, valid/invalid `aws lambda invoke` commands with the qualified-ARN requirement, concrete IAM permission names, and specific Python API differences. It falls just short of score 5 due to minor gaps such as `Duration.from_seconds(n)` being referenced without showing its import, and the decorator form `@durable_step` being mentioned without a code example.

4 / 5

Workflow Clarity

Ordering guidance is present ("Read these before writing any code"), navigation by task is explicit, and there are two explicit ALWAYS-check checklists (replay-model violations when writing/reviewing code; test verification rules). It is not score 5 because the body itself never lays out an explicit numbered build sequence — sequencing is delegated to getting-started.md — so the main workflow's checkpoints are present but the end-to-end order is implicit.

4 / 5

Progressive Disclosure

The body is a clear ~130-line overview with a "When to Load Reference Files" section mapping eleven topics to eleven real, substantial reference files, all one level deep and verified to exist in references/. A few sibling files carry lateral "see also" pointers (advanced-patterns.md → advanced-error-handling.md), but no content is hidden behind nested chains, matching the score-5 anchor (clear overview, well-signaled one-level-deep references, easy navigation) rather than score 4's 'minor organization gaps'.

5 / 5

Total

17

/

20

Passed

Description

96%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong description: third-person voice, concrete multi-part capability statement, and an explicit trigger clause with comprehensive keyword coverage including SDK identifiers. The only weakness is a handful of broad trigger terms (state machines, workflow orchestration, reliable serverless applications) that create minor overlap risk with adjacent orchestration skills.

Suggestions

Qualify the generic trigger terms — e.g. "state machines" → "durable state machines on Lambda" and "workflow orchestration" → "Lambda workflow orchestration" — so they are less likely to fire for Step Functions or non-Lambda orchestration requests.

DimensionReasoningScore

Specificity

The description lists multiple concrete capabilities — "automatic state persistence, retry logic, and orchestration", "the critical replay model, step operations, wait/callback patterns, error handling with saga pattern, testing with LocalDurableTestRunner" — covering the domain comprehensively. It matches the score-5 anchor (multiple specific concrete actions, comprehensive coverage) rather than score 4, which would require noticeable gaps in coverage.

5 / 5

Completeness

It explicitly answers "what" ("Builds resilient, long-running, multi-step applications... with automatic state persistence, retry logic, and orchestration") and "when" via an explicit trigger clause ("Triggers on phrases like lambda durable functions, durable execution, ..."). This matches the score-5 anchor with concrete trigger phrases, not score 4 where the 'when' would be less explicit.

5 / 5

Trigger Term Quality

Trigger coverage is comprehensive and spans both natural user phrasings ("lambda durable functions", "durable execution", "saga pattern", "human-in-the-loop callbacks", "long-running stateful Lambda functions") and exact identifiers a user might paste ("context.step", "withDurableExecution", "UnrecoverableInvocationError", "durable-execution-sdk", "qualified ARN invocation"). This matches the score-5 anchor including synonyms; not score 4 because no common natural variation is obviously missing.

5 / 5

Distinctiveness Conflict Risk

The niche is clear and anchored by distinct SDK-specific triggers ("withDurableExecution", "durable-execution-sdk", "qualified ARN invocation", "durable handler replay"), but generic terms like "state machines", "workflow orchestration", and "reliable serverless applications" could also fire for closely related skills such as a Step Functions or general orchestration skill. This fits the score-4 anchor (mostly distinct, minor overlap risk with closely related skills) rather than score 5, which requires minimal conflict risk.

4 / 5

Total

19

/

20

Passed

Validation

93%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 15 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

frontmatter_unknown_keys

Unknown frontmatter key(s) found; consider removing or moving to metadata

Warning

Total

15

/

16

Passed

Repository
aws/agent-toolkit-for-aws
Reviewed

Table of Contents

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