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

Annotations already declare readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds real behavioral context beyond that: results are bounded by the plan's retention, ordering is newest-first, a range summary appears on the first page, and pagination terminates when exhausted is true.

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 dense sentences with zero filler, front-loading the resource and scope, then ordering, retention, and pagination. Every clause carries information an agent needs.

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 takes on return-value disclosure and does so reasonably: it explains ordering, the first-page range summary, retention bounding, and pagination termination. It does not detail the summary's contents or the event shape, but it covers enough for correct invocation.

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 83%, so the schema already documents most parameters (user_ids exact match, since/until forms, cursor). The description restates that user_ids are matched exactly against the raw event user_id but adds little syntax or format detail beyond the schema, so the baseline of 3 applies.

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?

States a specific verb and resource ('The timeline of one customer: every raw event whose user_id matches...'), plus ordering (newest first) and scope (single customer). This clearly differentiates it from siblings like search_events and get_event, which an agent can distinguish without opening a schema.

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 tells the agent how to paginate ('Page with next_cursor until exhausted is true'), which is useful procedural guidance, but never states when this tool is preferable to search_events or get_event, nor any usage exclusions. Usage is implied rather than explicitly directed.

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