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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful context about auth ('via your connected GitHub account') and return fields, but says nothing about pagination behavior, result ordering, or what happens at the default limit of 50 – with only one annotation, the bar is lower but these gaps remain.

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 sentences, front-loaded with the core action and scope. The return-field enumeration is mildly redundant given no output schema, but the routing guidance earns its place. No filler.

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?

Complete for a read-only, two-optional-param listing tool. The description covers purpose, discovery role, and filter behavior; the missing pieces (pagination, ordering) are minor for an agent whose primary need is knowing which tool to call first.

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 both 'limit' and 'search' are already documented in the schema. The description reiterates that search is for specific repositories but adds no syntax, matching behavior, or format details beyond the schema, so 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?

Specific verb (List) plus resource (GitHub repositories) and scope ('you have access to via your connected GitHub account'). It also enumerates returned fields (names, owners, default branches, visibility), clearly separating it from github_search_code and github_list_repository_files.

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?

Explicitly states 'Use this first to discover owner and repo names before using other GitHub tools,' and names the search filter as the tool for a specific-repository lookup. The when-to-use context and the alternative path are both spelled out.

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