github_compare_branches

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

With no annotations, the description must carry the full transparency burden. It does disclose the output behavior (ahead/behind counts and changed files) and the action 'compare' implies a read-only operation. However, it omits any caveats about error cases, branch existence, or output limits.

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 concise: one clear sentence followed by an efficiently formatted Args block. Every element earns its place, especially given the need to compensate for missing schema descriptions.

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?

The tool is simple, and the description adequately covers its purpose, parameters, and output. Since an output schema exists, the description doesn't need to detail return values. Minor gaps remain around edge cases like non-existent branches or pagination, but they are not critical for basic usage.

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?

Although the schema has 0% description coverage, the description's Args block thoroughly explains each parameter (owner, repo, base, head, session_name) and even provides examples for base and head. This fully compensates for the schema's lack of descriptive text.

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 action and output: 'Compare two branches showing ahead/behind counts and changed files.' This is a specific verb+resource combination that distinguishes it from sibling tools like get_branch or list_branches.

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?

The description provides no guidance on when to use this tool versus alternatives, nor any exclusions or prerequisites. It simply states what the tool does, leaving the usage context entirely to the user.

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