list_direct_messages

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description's 'Fetch' aligns with read-only behavior. However, it adds no additional behavioral context beyond the schema (e.g., pagination, rate limiting, or note that results may change). With annotations carrying the burden, a baseline score is appropriate.

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 concise—a single sentence with no wasted words. It front-loads the core action. However, it could be slightly improved by including a brief note on tabs or pagination without becoming verbose.

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?

Despite having annotations and 3 parameters, the description lacks important context: no mention of pagination (cursor usage), no explanation of openWorldHint implications, and no guidance on the tab parameter's effect on results. A minimal description for a tool with this complexity is insufficient.

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 67% (tab and count have descriptions; cursor lacks one). The description adds no parameter-level information. Since schema already explains tab and count adequately, the description does not need to repeat them, but it could clarify the cursor's role in pagination. Baseline score of 3 is justified given incomplete coverage.

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 clearly states the tool fetches Twitter direct messages via API. While generic, it distinguishes from siblings like send_direct_message and get_direct_message_conversation through context (listing vs sending/single conversation). Could be more specific about scope (e.g., across all conversations) but is adequate.

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 usage guidelines are provided. The description does not specify when to use this tool vs alternatives like get_direct_message_conversation, nor does it mention when not to use it or any prerequisites. This lack of guidance forces the agent to infer context from sibling names.

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