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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower; the description nonetheless adds real context by disclosing ordering (newest first), row composition (source_table/source_id), and that long metadata values are truncated excerpts.

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 tight sentences with no waste: the resource and ordering constraint are front-loaded, and the second sentence earns its place by defining the row shape and the truncation behavior.

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 the return-shape burden and does so (rows indexing a document, newest-first, excerpt truncation). Annotations cover safety, so the only omission is pagination behavior beyond the limit parameter.

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% for both parameters (contact_id uuid, limit default 50 max 500), so the schema does the heavy lifting. The description adds no meaning about contact_id or limit beyond that, making the baseline 3 appropriate.

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+resource: the activity timeline for a contact, with ordering ('newest first'). It is distinguishable from get_contact (the record itself) and list_contacts by the 'what happened' framing, but it never explicitly names a sibling as the alternative.

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?

'An index of what happened' implies the browsing/history use case, so intent is inferrable, but there is no explicit when-to-use guidance and no mention of when to prefer get_contact or search_contacts instead. Adequate but with a clear gap.

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