gh_issue_comment

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

No annotations are provided (no readOnlyHint, no destructiveHint), so the description carries the full burden. It states the action is 'add' which implies mutation (creating a new comment), but it doesn't disclose behavioral details such as whether the comment is appended to a thread, whether it first requires the issue to exist, whether it requires authentication/permissions, or what it returns. For a write tool with zero annotation coverage, more behavioral disclosure would be expected, but the mutating intent is at least unambiguous.

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 with zero wasted words. It states the complete purpose efficiently and has no redundant phrasing or 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?

The tool is simple (3 required params, no nested objects, no output schema). Given this modest complexity, the description plus schema is minimally adequate. However, it lacks context about what the operation returns, whether the comment appears immediately, or whether an existing issue is verified, and there are no sibling-differentiating hints. For a simple mutation tool without annotations, it meets the minimum but doesn't excel.

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 three parameters (body, repo, number). The schema descriptions are reasonably informative, including the notable note on repo ('a write never infers its target'). The description adds no additional parameter context beyond the schema, so the baseline of 3 is appropriate — the schema does the heavy lifting.

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 'Add a comment to a GitHub issue' clearly states the verb (add) and resource (comment on a GitHub issue). It distinguishes from siblings like gh_issue_create (creates issues vs comments) and gh_issue_edit (edits issues). It's specific enough to convey the action, though it doesn't elaborate on whether it appends a new comment vs updating, which makes it slightly less than a 5.

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 provides no explicit when-to-use or when-not-to-use guidance. It doesn't contrast with gh_issue_create or gh_issue_edit, so an agent must infer that this tool is for threading a new comment onto an existing issue. The comment-targeting context is implied by the tool name and resource ('issue'), but there's no explicit alternative guidance or prerequisite note (e.g., 'issue must exist').

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