Reply to PR comment

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

Annotations already indicate the tool is a non-read-only, non-destructive write operation. The description adds valuable behavioral context: for inline comments, path and line are inherited from the parent comment. This explains threading semantics beyond what annotations convey.

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, front-loaded with the core purpose, followed by targeted guidance about a potential misuse. No redundant or fluff content.

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 reply tool, the description covers purpose, usage, and the key threading behavior. It lacks explicit return value details, but no output schema is present and the description sufficiently enables correct invocation.

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?

The schema has 100% description coverage for all five parameters, so the baseline is 3. The description adds a note about comment_id's role in threading and parent inheritance, but it does not elaborate on other parameter formats or values beyond the schema.

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 states a specific verb 'reply' and resource 'PR comment' with the outcome 'threaded reply.' It explicitly distinguishes itself from the sibling tool add_pr_inline_comment, clarifying that this tool creates a threaded reply rather than a sibling comment.

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 clear when-to-use context: reply to an existing comment to create a threaded reply. It also provides an explicit exclusion: do not use add_pr_inline_comment because that posts a sibling comment, naming the alternative and its consequence.

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