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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds only the action semantics already implied by the enum, saying nothing extra about pagination behavior, result size, or rate limits. With annotations doing the heavy lifting, this is adequate but not additive.

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, no filler, with the overall purpose front-loaded and the two actions enumerated immediately after. Every clause earns its place by mapping an action to its behavior.

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 read-only two-mode tool with a fully documented schema and annotations covering safety, the description is nearly sufficient: an agent knows both modes and the path filter. It would be complete with a brief note that 'diff' requires a sha and that results are paginated via page/limit, but nothing critical 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 coverage is 100%, so every parameter (sha, path, page, limit, owner, repo) is already documented in the schema with per-action applicability notes. The description only restates the path filter for 'list', adding no syntax or format detail beyond the schema, so the baseline 3 applies.

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 gives a clear verb+resource ('Browse commit history and view diffs') and enumerates the two concrete actions, so an agent immediately knows the tool's scope. It does not compare itself to any sibling tool, but overlap with siblings like 'branches' or 'files' is low enough that differentiation is not a gap.

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?

It states the selection rule between the two modes: 'list' for listing commits (optionally path-filtered) and 'diff' for a single commit's unified diff. No explicit exclusions or prerequisites are given (e.g., that a sha is needed for diff), but the action routing is unambiguous.

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