git_diff

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the read-only nature is covered. The description adds limited behavioral context by listing comparison targets, but it doesn't disclose any additional traits like output format defaults or merge-base behavior. Since there is no contradiction, a neutral score is appropriate.

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, well-structured sentence that immediately conveys the core function. It is front-loaded with the verb and resource, contains no filler, and every word contributes meaning. This is exemplary conciseness.

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?

Given the tool has 9 parameters, enums, and a sibling list of 14 git tools, this one-line description is inadequate. It does not clarify the meaning of modes, when to use this versus comparable siblings, or how the output schema might vary by format. Annotations and output schema help, but the description leaves too many gaps for an agent to confidently select and invoke it 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 only 33% (3 of 9 parameters have descriptions), so the description must compensate for the missing parameter semantics. However, it does not elaborate on the meaning of 'base', 'head', 'mode', 'path', 'format', etc. The only hint is that 'working tree, index, HEAD, or two revisions' maps roughly to the 'mode' parameter, which is insufficient for a tool with this many parameters.

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's function with a specific verb ('Compare') and resource scope ('working tree, index, HEAD, or two revisions'). It is not tautological and gives a good sense of what the tool does, though it doesn't explicitly distinguish from siblings like git_range_diff or git_compare_refs.

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?

No guidance is provided on when to use this tool versus alternatives such as git_compare_refs or git_range_diff. The description mentions the objects that can be compared but does not offer context on selection criteria, prerequisites, or exclusions. This leaves the agent without clear decision support.

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