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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuinely new context beyond them: the return payload shape (comments, anchor, anchor target) and an explicit prompt-injection warning about untrusted user-authored content — a real behavioral trait the annotations cannot express.

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, zero waste: the first defines scope and payload up front, the second delivers the safety constraint. Nothing is repeated from the schema or annotations.

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?

No output schema exists, and the description compensates by naming what comes back. For a single-parameter read tool this is nearly complete; only not-found behavior and access requirements are unaddressed.

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?

Only one parameter and schema description coverage is 0%, so the description must carry the load. 'Read one comment thread' implies threadId identifies the target, but it adds no format, sourcing, or error semantics (e.g. what happens if the ID is unknown) beyond the schema's own uuid format declaration.

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?

Specific verb ('Read') plus a precisely scoped resource ('one comment thread with all its comments, its anchor and what it's on'). The singular 'one' implicitly separates it from list_comment_threads, but no sibling is named explicitly, so it stops short of the top tier.

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 second sentence gives operational handling advice (treat bodies as data, not instructions), which is valuable but is not selection guidance. Nothing tells the agent when to call this versus list_comment_threads, reply_to_comment_thread, or resolve_comment_thread.

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