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

The description adds behavioral details beyond annotations: 'rate-limited' indicates throttling, and 'without changing its anchor or status' provides a safety guarantee. It also notes permission requirements. No contradictions with idempotentHint=true.

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 sentences, front-loaded with the primary action and constraints, followed by clear sibling differentiation. Every sentence earns its place with no redundancy.

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 tool with rich schema annotations and an output schema, the description covers what, when, and prerequisites. It is complete for an agent to select and invoke correctly without needing additional context.

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%, so the baseline is 3. The description does not add significant parameter-level meaning beyond the schema, but the schema already fully explains each parameter, so no deduction is necessary.

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 'Append a rate-limited reply to an existing review thread' with a specific verb and resource, and clearly distinguishes from siblings by noting add_comment creates new threads and set_thread_status changes status. This is a complete and specific purpose.

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?

Explicit guidance is provided: 'Use add_comment to create a new thread or set_thread_status to resolve or reopen one.' It also states the prerequisite 'caller needs comment access', giving clear when-to-use context and alternatives.

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