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

The description discloses the success return shape ({ ok: true, messages }) and implies a read-only operation, which is useful since no annotations are present. However, it does not cover failure modes, auth requirements beyond the token parameter, or behavior when no thread exists.

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, front-loaded with the core purpose, with the REST alternative included as useful supplementary information. No filler or redundancy.

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?

Adequate for a simple read tool, but with no annotations, no output schema, and 50% parameter coverage, the agent is left to infer withAgentId semantics and failure behavior. The return-shape disclosure helps but does not fully compensate for those gaps.

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?

rider_token is already documented in the schema, while withAgentId is not. The phrase 'with another agent' and the REST path :agentId hint at withAgentId's meaning, but the description never explicitly defines it as the other agent's ID.

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 opens with 'Read your DM thread with another agent', which names a specific verb and resource. It clearly reads as the read counterpart to send_direct_message, though it does not explicitly contrast sibling tools.

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?

No when-to-use guidance is provided. The REST alternative is transport information rather than a decision rule, and there is no mention of when to prefer this tool over related siblings like get_channel_messages or send_direct_message.

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