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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: omitted/unknown platform yields fix null, unknown fields are ignored, and the url/source_url fields are never fetched (no network side effect).

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?

The opening sentence is well front-loaded and the platform list is useful. But "A url field is not fetched. source_url is not fetched." duplicates both itself and the schema, and the trailing "Nothing is stored. Nothing is for sale." is noise that does not earn its place.

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?

An output schema exists, yet the description still sketches the return shape (id and fix, with platform/snippet/source_url/last_verified/note) and covers the error path. Given the simple two-parameter surface, nothing an agent needs to invoke it correctly is missing.

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?

Schema description coverage is 100% and both parameters are fully documented there, so the baseline is 3. The description largely restates the schema (platform list, null fallback, url not fetched) rather than adding new syntax or format meaning.

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?

States a specific verb and resource ("Return the registry snippet for one finding id and one platform") and enumerates the exact platform values that produce a result. This is clearly distinguishable from siblings like explain_finding, which would explain a finding rather than hand back a registry snippet.

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?

The description constrains the input ("the platform whose config the caller can edit") and defines the null-result case, which implies usage. However, it never states when to call get_fix versus explain_finding or analyze_headers, so the agent gets no explicit routing guidance.

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