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

With no annotations provided, the description fully carries the behavioral burden. It discloses the default pagination direction, the meaning of the 'earlier' field (which would be in the response), the exact preservation of 'body' text (critical for matching edits), the 'replyTo' field semantics and how to use it with add_comment, that deleted comments are omitted, and the permission requirement. This is comprehensive and adds significant value beyond the schema.

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?

The description is dense and packed with useful information, front-loaded with the core purpose. It is somewhat long, but every sentence contributes to usage, pagination, or response semantics. While it could be slightly tightened, the length is justified given the complexity of pagination and the lack of an output schema. It is well-structured and not verbose.

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?

Given that there is no output schema, the description compensates by explaining response fields (body, replyTo, earlier) and the pagination mechanism. It covers permission requirements and the default behavior. It provides all necessary information for an agent to call the tool correctly and interpret the response, making it complete for a read operation.

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 already provides descriptions for all three parameters (100% coverage), but the tool description adds valuable semantic context beyond the schema. It clarifies that startAt is counted from the oldest comment, explains the default behavior when startAt is omitted, and provides a concrete pagination recipe ('pass startAt - limit from a previous answer'). This goes beyond the schema's basic field descriptions.

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 clearly states the tool reads comments on an issue, with a specific verb ('Read') and resource ('discussion on an issue'). It distinguishes itself from comment-writing siblings like add_comment and update_comment by focusing on reading. The opening sentence is unambiguous and leaves no doubt about the tool's purpose.

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 explicit guidance on when to use the tool (to read discussions) and explains the default pagination behavior (most recent comments) and how to walk back with startAt. It also notes that it is needed to fetch the text for update_comment edits, and states the only permission required. It does not explicitly name alternatives, but the context of siblings makes it clear this is the read tool for comments.

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