Show diff (side-by-side image)

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

With no annotations provided, the description carries the full burden and adequately discloses key behaviors: it returns an inline image, defaults to uncommitted changes, and can target a checkpoint sha. It does not mention side effects or limitations, but for a read-only rendering tool this is sufficient.

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 core action, and every clause adds value. No fluff or repetition.

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 simple one-parameter tool with no output schema, the description is complete: it explains what the tool returns, the default behavior, how to get a specific version, and when to use it. No gaps for a typical use case.

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 parameter 'checkpoint' is fully described in the schema. The tool description reiterates the checkpoint behavior but adds no new semantic detail beyond what the schema already provides, so 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 clearly states 'Render a side-by-side git diff as an image' with a specific verb and resource, and distinguishes it from a text summary. It also differentiates from siblings by focusing on visual diff rendering rather than previews or comments.

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?

Explicitly says 'Use this when the user asks to SEE a diff visually' and clarifies it returns a picture, not text. It provides context on default behavior and checkpoint usage, though it does not name a specific alternative tool for text diffs, so it stops short of full when-not guidance.

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