x_api_create_direct_messages_by_participant_id

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

With no annotations, the description carries full burden and does well. It discloses the mutating, high-risk nature, required OAuth scopes, environment-selection behavior for tenant principal resolution, expected response shape, common failure conditions, and explicit safety warnings. This goes far beyond a basic tool description and gives the agent a solid behavioral model.

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 well-structured with labeled sections (Use when, Risk, Permissions, Environment-selection, Parameters, Response, Failures, Prerequisites, Safety, Example). Each section adds unique value, and the example is useful. It is longer than typical but appropriately so for a complex tool with no annotations. No redundant filler.

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 the tool's complexity (8 params, no output schema, no annotations), the description covers most critical aspects: auth requirements, environment selection, failure modes, response shape, and safety. It falls short only on fully documenting all parameters (notably authorizationKey and preferredAuthType) and the body structure, but overall it provides a strong operational context.

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 0%, so the description must compensate. It explains participant_id as path/required and body as the request payload, and clarifies the roles of scopeTenantId, scopeUserId, scopeAccountId, and credentialKey in environment selection. However, it leaves authorizationKey and preferredAuthType unexplained, and the body schema is unspecified. Partial compensation for a low-coverage schema.

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 a clear, specific verb+resource: 'Create DM message by participant ID.' This distinguishes it from sibling tools like x_api_create_direct_messages_by_conversation_id and x_api_create_direct_messages_conversation by specifying the unique identifier (participant ID). The purpose is immediately unambiguous.

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 'Use when' section merely restates the purpose ('Create DM message by participant ID'), which is tautological. However, the 'Do not use when' guidance provides some direction, advising against using this tool when auth/config setup is needed or when exploring, preferring x_schema_discovery or x_query_suggestion first. It does not explicitly contrast with sibling DM-creation tools, so the guidance is partial but present.

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