Send a Direct Message

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

Annotations indicate a write operation (readOnlyHint=false) and side effects (openWorldHint=true). The description adds meaningful context: confirmation requirement, anti-spam guardrails, and the single-conversation constraint. It fully discloses the operational behavior beyond the annotations, with no contradictions.

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, every sentence carries operational weight, and the core action is stated first. No fluff or repetition; it efficiently packs recipient options, confirmation, media linkage, and spam restrictions into a few lines.

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?

With no output schema, the description should explain expected outcomes or errors, but it doesn't mention return values, failure behavior, or rate limits. It covers prerequisites and constraints well, but for a 6-parameter write operation, missing response semantics leaves a gap for the agent to guess.

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 coverage is only 33%, so the description must compensate. It clarifies that participant_id and username are alternative recipient identifiers, dm_conversation_id is an existing conversation, and media_id is optional from upload_media. It also explains confirm's requirement. Not every parameter is detailed (e.g., text is obvious), but the description adds meaningful semantics for the ambiguous ones.

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 states a specific verb ('Send'), a clear resource (a direct message to a named recipient or existing conversation), and distinguishes itself from siblings by being the DM-specific tool. It also scopes the action to a single DM with no bulk, which prevents confusion with posting 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?

The description gives explicit conditions: requires confirm=true after an explicit ask, never invent copy, one recipient, no bulk unsolicited DMs. It also mentions the optional media_id from x_organic_upload_media. While it doesn't explicitly contrast with public replies, it provides enough contextual rules to guide appropriate use.

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