Read repository file

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds 'complete contents and blob metadata', clarifying the exact data scope, and reinforces safety ('never modifies GitHub'). This adds context beyond the annotations without being redundant.

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, zero filler. The most critical information ('Read-only', 'one repository file', 'never modifies GitHub') is front-loaded. Every word serves a purpose, and the structure is scannable.

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 single-file read tool with an output schema and full parameter coverage, the description is complete. It covers the operation, target scope, and safety profile without unnecessary detail. No gaps in context are apparent given the simple use case.

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 baseline 3 applies. The description clarifies that 'branch, tag, or commit ref' are valid for the ref parameter, aligning with but not exceeding the schema's parameter descriptions. No additional semantic value beyond the schema is provided.

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?

Specific verb 'fetch' + resource 'complete contents and blob metadata for one repository file' + scope 'at a branch, tag, or commit ref'. This clearly differentiates from sibling tools like gh_get_commit or gh_get_repo, making the purpose unmistakable.

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 indicates read-only usage ('Read-only', 'never modifies GitHub') but does not explicitly state when to prefer this tool over alternatives or mention exclusions. Usage is implied through the description but no direct comparison or when-not-to-use is provided.

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