add_issue_comment

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

Annotations only declare the generic profile (readOnly=false, openWorld=true, idempotent=false, destructive=false). The description adds three concrete behaviors the annotations cannot express: a repository allowlist that is currently empty, a 2000-character cap, and a server-wide DRY-RUN mode where nothing is posted and the response echoes what would have been sent. These are exactly the facts an agent needs before calling a mutating 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?

Three short sentences with zero filler, front-loaded with the core action and followed by the two hard constraints. Every sentence carries information the agent could not get from structured fields.

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 no output schema, the description takes on the burden of explaining the return value, and it does: 'you get back what would have been sent.' Combined with the allowlist and dry-run disclosures, an agent has everything needed to decide whether to call the tool and how to read the result.

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 the baseline is 3. The description still adds real meaning beyond the schema by imposing a 2000-character limit on the body parameter, which is not encoded as maxLength in the schema. Owner/repo/number need no elaboration given their schema descriptions and patterns.

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 precise verb+resource: 'Add a comment to an issue or pull request.' That makes it immediately distinguishable from every sibling (list_issues, get_issue, list_pull_requests, get_pull_request, search_issues), all of which are read tools. It stops short of explicitly naming a sibling alternative, which keeps it just below 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 gives strong operational context: it only works on allowlisted repositories and none are configured, so the agent knows invocation will not actually post anything. The DRY-RUN note further frames when and how the result should be interpreted. It lacks an explicit 'use this instead of X' routing statement, but for a write tool whose siblings are all reads, the guidance is clear.

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