Comment on a GitHub issue

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

Beyond the annotations it discloses real side effects: followers are notified and the comment persists on the issue. It also states the write-permission requirement, which annotations alone do not convey. It stops short of covering rate limits or whether the comment can later be modified through this tool.

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, action and effects first, prerequisites and parameter formats second — no filler. Every clause (notification, persistence, permission, reference formats) carries information an agent would otherwise have to guess.

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 three-parameter mutation tool with full schema coverage, an output schema, and rich annotations, the description supplies the prerequisites, side effects, and reference-format guidance needed to call it correctly. Additional detail, such as whether the posted comment is returned, is already covered by the output schema.

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 is 3, but the description adds meaning by spelling out the fallback rule — a bare number resolves against the working tree's repository or the repo parameter. That interaction between the issue and repo parameters is not stated in the schema itself, though the issue-format list is repeated verbatim.

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 opens with a specific verb and resource ('Post a comment on an issue') and its effect ('the comment stays on the issue') distinguishes it from siblings such as github_issue_relate or github_issue_create. An agent can tell exactly which of the eight issue tools this is without opening a 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?

It gives the implicit context for use (posting a comment) and a prerequisite, write permission, but never names an alternative or states when not to use it. With siblings like github_issue_edit and github_issue_read available, an explicit contrast would have improved routing.

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