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

The annotations already declare this is a safe read-only operation, but the description adds useful behavioral details: results are ordered by newest activity first and include message_count and unread_for_user. It does not discuss limits or pagination, but the output schema likely covers return structure.

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 compact and front-loaded: it states what is returned, the ordering, key fields, and the primary use case. Every sentence contributes useful 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 this is a zero-parameter read-only listing tool with an output schema and clear annotations, the description provides sufficient context. It explains ordering, included fields, and the primary follow-up action.

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 tool has zero parameters, so there is no parameter semantics to disambiguate. The baseline for zero-parameter tools is 4.

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 and resource: lists the user's support threads. It also distinguishes the tool's role from read/continue tools by framing it as the way to find a conversation_id, so an agent can identify it without opening the schema.

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 clearly states when to use the tool: to find the conversation_id of an earlier thread to continue or read, including threads opened in another session. It does not explicitly name alternatives or exclusions, but the intended usage context is clear.

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