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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered; the description adds genuinely useful context beyond that — the unauthenticated rate limit of ~10 requests/minute — which an agent needs for planning request volume. It does not, however, describe pagination behavior or result caps.

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?

Three short sentences, front-loaded with the verb and scope, then rate limit, then the sibling routing. The 'q: GitHub repository search query' clause duplicates the schema verbatim and is the one expendable sentence.

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?

With an output schema present, the description need not explain return values, and it covers purpose, rate limits, and the closest alternative. It is slightly thin on the broader Github sibling set (repo/org/trending lookups), but nothing required to invoke it correctly 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 description coverage is 100%, so the schema already documents all five parameters including sort, order, and per_page. The description only echoes q, adding no syntax, query-operator, or format guidance 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?

States a specific verb and resource ('Searches public GitHub repositories'), names the return shape ('repository rows'), and gives the intent ('market or competitive discovery'). It also explicitly distinguishes itself from the sibling github_search_users, so an agent can route 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?

Names the alternative github_search_users and the condition that selects it ('to search public GitHub users'), which is a clear routing rule. It stops short of covering the other close siblings (github_repo, github_org_repos, github_trending) or stating when a single-repo lookup is preferable.

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