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

Goes well beyond the readOnly/idempotent annotations: it specifies newest-first ordering, discloses pagination mechanics (pass next_before as `before`), explains the `by` and `via` attribution fields with enumerated values, notes that each entry carries contact_id where applicable, and calls out that the call is free. That is substantial behavioral context an agent could not infer from the schema.

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 core purpose is front-loaded and nearly every clause carries real information, but the description is one dense run-on paragraph of colon-delimited lists that is hard to scan, and the trailing "Free." is an isolated fragment. Structuring the pagination and by/via explanations as separate sentences would improve it.

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?

For a 7-parameter, no-required-argument read tool with no output schema, the description covers scoping, ordering, pagination, and attribute semantics well. The remaining gap is the response shape (what fields each entry exposes beyond contact_id) and the role of `email` and `limit`, though those are secondary.

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 29%, so the description must carry more weight; it does explain scoping semantics (company_id implies all its people, no id means whole CRM) and the before/next_before cursor. However, `limit`, `email`, and the enumerated `types` parameter are not addressed in the description, leaving several parameters to the bare 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?

States a specific resource (timeline of everything that happened) with explicit scope: a contact, a company including all its people, a deal, or the whole CRM when no scope is named. It enumerates the entry kinds (notes, tasks, emails, chats, calls, tickets, meetings, deal stage moves) so an agent can distinguish it from narrower siblings like crm_list_tasks or account_list_calls.

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?

Gives a concrete triggering rule: "Read it before you write to someone," which tells the agent when to reach for this tool. It does not name alternatives (e.g., crm_search or crm_get_contact) or state when not to use it, so it falls short of a full routing statement.

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