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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so the safety profile is covered. The description adds genuinely useful non-annotation context: it is free (no cost), and it defines what the diff is measured against (the last commit, not live state).

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?

Three short sentences, front-loaded with the operation and its scope before the usage hint, with no filler. 'Read-only' mildly duplicates the readOnlyHint annotation, which is the only wasted fragment.

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?

An output schema exists, so return values need no explanation, and the annotations cover safety. For a two-parameter read tool the description is nearly sufficient; only the parameter formatting/identifier semantics remain unaddressed.

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 0%, so the description bears the full burden for both parameters. 'One project file' implicitly maps to project_id and file_path, but neither parameter's expected format (integer project id, repo-relative vs absolute path) is clarified anywhere.

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?

States a specific verb and resource ('Git diff of one project file against the last commit') with explicit scope, distinguishing it from read_file and list_commits by naming what is compared (working tree vs last commit). The parenthetical 'pending (not yet live) changes' further disambiguates the output from a file listing.

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?

'Use after edits to review exactly what changed before rebuilding' gives a clear triggering context and a natural workflow position (post-edit, pre-build/publish). It does not name alternative tools such as read_file or list_commits, so it stops short of explicit when-not/alternative guidance.

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