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

Annotations already indicate read-only, non-destructive, idempotent behavior. Description adds context about the is_participant field and the prerequisite for joining modmail, which is beyond annotations. No contradiction.

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 concise sentences. First sentence states purpose and ordering. Second sentence adds critical usage nuance. No redundant information.

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 an output schema exists (not shown) and there are many sibling tools, the description covers the essential: listing threads, ordering, and prerequisite for reading. Missing explicit pagination or filtering details, but acceptable for a simple list 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?

Single required parameter colony_name is fully described in the schema (100% coverage). The description does not add additional meaning beyond what is in the schema, so baseline score of 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?

Description clearly states the tool lists modmail threads for a moderated colony, sorted by newest activity. The verb 'list' paired with 'Modmail threads' and the qualification 'for a colony you moderate' precisely defines the scope. Distinguishes from siblings like colony_join_modmail.

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?

Provides explicit condition about is_participant field and directs to use colony_join_modmail when false, which helps the agent decide when to use this tool versus join. However, does not explicitly mention when not to use this tool or compare to other listing tools like colony_list_conversations.

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