vcs_diff

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

With no annotations provided, the description carries the full behavioral burden, and all it offers is "Read-only." It does not disclose output shape, whether it requires a clean working tree, or whether uncommitted/staged changes are included.

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 terse fragments with no wasted words, but this is under-specification rather than conciseness; the brevity leaves the definition functionally empty.

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?

A zero-annotation, zero-output-schema tool with an undocumented parameter requires far more from the description than a name restatement and a read-only note. Nothing an agent needs to call this correctly is present.

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?

There is one parameter (path) at 0% schema description coverage, and the description never mentions it, so its meaning (file vs directory vs whole repo default) is entirely undocumented. The description does not compensate for the coverage gap.

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?

"VCS diff" essentially restates the tool name with no verb or explanation of what a diff operation returns. It does not distinguish this tool from sibling vcs_status or from search/fs_read that also surface change-related data.

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?

There is no when-to-use guidance, no prerequisites, and no mention of the obvious alternative (vcs_status) or whether a path is needed for a workspace-wide diff. The agent is left to infer everything.

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