review_diff

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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds behavioral context beyond annotations: it returns 'a structured CI verdict with file/line findings and nearest-token suggestions' and it explicitly specifies that only added UI-code lines are reviewed. No annotation contradiction is present.

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 three sentences, each with a distinct purpose: scope, return value, and call timing. There is no filler, and the most important information is front-loaded.

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?

Although there is no output schema, the description communicates the return value ('structured CI verdict with file/line findings and nearest-token suggestions') and the key inputs (DESIGN.md tokens, recorded decisions). Parameter schema fully covers the remaining configuration options, so nothing critical needed to call the tool 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%, so the schema fully documents all five parameters. The description adds minor context about added lines, but this is already represented in the parameter schema, particularly the diff-scoped behavior documented for fail_on. Baseline 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 opens with a specific verb ('review') and a clear resource ('added UI-code lines in a unified diff'), and names the comparison target ('DESIGN.md tokens and active recorded design decisions'). It also states the return shape ('structured CI verdict'). It stops short of a 5 because it doesn't explicitly name sibling alternatives or say what it is not.

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 gives an explicit invocation condition: 'Agents should call this on every PR or diff that touches UI code before merge.' This is clear usage guidance. It lacks explicit when-not-to-use guidance or alternative routing, so it doesn't earn a 5.

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