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

Annotations already declare readOnlyHint=true and openWorldHint=false. The description adds a genuinely useful behavioral detail beyond them: results come from hybrid keyword + semantic matching, which tells the agent results may not be exact literal matches. It omits pagination/result-size behavior, but the schema covers that.

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?

A single sentence, front-loaded with the verb and resource, with filters trailing. Nothing redundant or padded.

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 7-parameter search tool with no output schema, the description covers the primary filters but leaves the sort enum, pagination behavior and what a result contains unexplained. Adequate to start a call, not complete enough to call optimally.

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 71%, so the schema does most of the work (examples for query, topic, language, defaults for page/per_page). The description restates language, topic and star filtering but adds no meaning beyond the schema, and says nothing about sort, which is the only enum parameter.

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 specific verb (search) and resource (open-source GitHub repositories) plus the mechanism (hybrid keyword + semantic). It only implicitly distinguishes itself from siblings like similar_repos and topic_repos, so an agent must infer that this is the keyword-entry point rather than a discovery tool.

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?

Usage is implied by 'search by keywords' and the optional filters, but no sentence says when to prefer this over topic_repos or similar_repos. The agent must infer the routing decision from the sibling names alone.

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