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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds behavioral context beyond annotations: the ordering guarantee ('oldest first') and the practical purpose (avoid repeating replies). It doesn't mention pagination behavior, but the schema's cursor/limit parameters already imply that.

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 filler. The core behavior is front-loaded, and the usage guidance is a single actionable sentence. Every word earns its place.

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 read-only list tool with full schema coverage and safety annotations, the description is nearly complete. It could add pagination details, but the cursor/limit parameters in the schema already signal that. The 'oldest first' ordering is a nice completeness touch.

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. The description adds no parameter-specific detail beyond what the schema provides. Baseline 3 is appropriate.

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 uses a specific verb ('Return') and resource ('comment thread on an issue'), and adds ordering detail ('oldest first'). It clearly distinguishes from siblings like list_doc_comments and add_comment by focusing on reading the existing thread.

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 explicitly tells the agent when to use this tool: 'Read this before replying, so you answer what was actually asked and do not repeat a reply you already posted.' This is strong usage guidance that also implies when not to use it (when you need to post, use add_comment/edit_comment).

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