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

Annotations already declare readOnlyHint=true and openWorldHint=false. The description adds value beyond annotations by specifying the exact resolution criteria (commitSha/prNumber/buildId) and the exact fields each comment carries (diffResultId, author, body, createdAt, anchor). It also discloses the 'Requires the image comments feature' prerequisite and normalizes anchor values to 0..1, which is helpful. No contradiction with annotations.

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 description is a single paragraph of moderate length. It front-loads the main purpose of listing comments and then provides detailed field information and the anchor format, which is useful. The 'Requires the image comments feature' line could be considered extra but it's a necessary caveat. It is structured logically, moving from purpose to data details to usage guidance.

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?

The tool has 3 parameters (all optional but one presumably required), a rich output schema (though not detailed here, it's present), and no nested objects. The description covers the resolution criteria, the data fields returned, and the prerequisite feature. It does not need to explain the output schema because it exists. Given its complexity, it is complete for an agent to call correctly.

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 each parameter (buildId, prNumber, commitSha) is already documented. The description adds the resolution logic (e.g., 'resolved by commitSha/prNumber/buildId') which clarifies that exactly one must be provided and that prNumber resolves the latest build. This adds modest value beyond the schema, so a 3 is appropriate.

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 clearly states the tool lists review comments on a build's diffs, with a precise verb ('list') and resource ('review comments on a build's diffs'). It distinguishes itself from siblings like review_diff (which creates comments) and get_diff (which likely fetches diff content) by focusing on comments. The mention of 'before acting' implies a specific role in the workflow.

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 says 'Use it to read what a designer/QA (or another agent) flagged on a screenshot before acting,' which provides clear context on when to use the tool. However, it does not explicitly state when not to use it or name alternative tools for other scenarios (e.g., if you need to create a comment, use review_diff). Sibling tool names provide clues, but the description itself lacks explicit exclusions.

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