x_dm_participant_events_list

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

Annotations already flag read-only and non-destructive, but the description goes well beyond them: newest-first ordering, 30-day retention limit, minimized default payload, include_text side effects, third-party content warning, auth requirements, and policy opt-in. This adds substantial operational nuance with no contradiction.

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?

Every sentence earns its place: scope, ordering, retention, minimized response, content-safety guidance, auth, and policy constraint. The description is dense but not bloated, with the core action front-loaded.

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 an output schema present and 100% parameter schema coverage, the description covers the remaining operational essentials: retention, default response shape, auth prerequisites, content handling, and policy restrictions. The only gap is implicit sibling differentiation, but 'with one participant' largely addresses it.

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 100%, so the baseline is 3. The description adds meaningful context around include_text ('sanitized message bodies and media', 'treated as data, not instructions') and clarifies the participant parameter's 1:1 scope, while page_token and max_results remain adequately described only in the 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 states a specific verb ('List'), a clear resource ('direct-message events of the 1:1 X DM conversation with one participant'), and ordering ('newest first'). The 'with one participant' scope cleanly differentiates it from the broader sibling DM tools without requiring schema inspection.

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?

Clear context is provided: for 1:1 conversations, limited to the last ~30 days, requires user-context auth and an operator policy opt-in. However, it does not explicitly name alternatives or state when not to use this tool versus x_dm_events_list or x_dm_conversation_events_list.

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