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

Beyond the annotations (readOnlyHint=true, openWorldHint=false), the description discloses cost (2 credits), that billing only occurs on successful calls, and that schema-invalid input is rejected before billing — material operational facts an agent won't find in structured fields. It does not discuss determinism or quality of the generated message, but the billing and validation semantics are the more important disclosure.

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?

Two tight sentences, front-loaded with purpose and return shape, then cost. The pricing clause is dense but justified because it affects invocation decisions; no filler sentences.

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?

There is no output schema, but the description compensates by listing the returned object's fields ({ message, type, scope, subject, body }), and it covers the single input's constraint and cost model. Complete enough to call correctly without opening anything else.

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 coverage is 100% and the single parameter already documents itself ('Unified diff (git diff output), up to 7,000 characters'). The description's 'unified diff' phrasing adds nothing beyond that, so baseline 3 applies.

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 opens with a precise verb+resource pair ('Turns a unified diff into a Conventional Commits message') and enumerates the produced fields, so an agent knows exactly what comes back. It does not name or differentiate against any sibling (e.g., text-diff, summarize), which caps it below a 5.

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?

Usage is only implied by the input type ('Turns a unified diff'), with no explicit when-to-use, when-not-to-use, or pointer to alternatives such as text-diff or summarize. An agent can infer the context but gets no routing guidance.

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