github_git_refs_get

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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds beyond them by disclosing what is actually returned (the commit SHA the ref points at), which matters because there is no output schema.

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, with the core action and return value front-loaded before the format detail. Nothing is padding and every clause carries information.

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 simple read tool with a fully documented 3-parameter schema and annotations covering the safety profile, the description is nearly complete, and it compensates for the absent output schema by naming the returned SHA. Minor gap: it does not note error behavior for nonexistent refs.

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% and the schema already documents ref, repo and owner identifiers. The description's format examples (heads/main, tags/v1.0, no refs/ prefix) duplicate what the schema says, so it adds no meaning beyond the structured field. 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?

States a specific verb and resource ('Get a reference and the commit SHA it points at') and even names the return value. It reads clearly against the sibling github_git_refs_create, since 'get' vs 'create' is unambiguous without opening either schema.

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 clause 'how you read a branch's current head before building on it' gives a concrete use context an agent can match to intent. It stops short of naming alternatives or exclusions, so it is clear context rather than a full when/when-not guide.

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