get_diagnostic_snapshot

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so 'Read-only; no files are modified' largely restates structured data. The genuinely additive detail is 'immutable' — the snapshot cannot change after recording — which is useful context versus a live query, but return contents are covered by the output schema and permission requirements are not mentioned.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences, front-loaded with the core action and scope. The 'Read-only; no files are modified' clause duplicates the annotations and the return-value list partly duplicates the output schema, but the overall size is appropriate and nothing is buried.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a one-parameter read tool with a rich annotation set and an output schema, the description covers purpose, scope, immutability, and return shape adequately. The missing piece is routing guidance against the many sibling diagnostic tools, but the essential call information is present.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With a single required parameter and 0% schema description coverage, the description does identify the key as a specific check run's id, giving the parameter some meaning. However it adds no syntax, format, or example, so an agent still learns nothing about what a valid checkId looks like.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource ('Retrieves the immutable diagnostic snapshot') scoped to a 'specific checkId'. The word 'recorded' plus 'checkId' distinguishes it from siblings like get_live_diagnostics and compare_diagnostics without needing their schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no explicit when-to-use or when-not guidance, and the obvious alternatives (get_live_diagnostics for current state, compare_diagnostics for cross-run comparison) are never named. The only hint is that a snapshot must already be 'recorded' for a checkId, which is implied rather than stated.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.