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

With no annotations, the description carries the full burden and discloses two valuable traits: "Read-only" (safe, no mutation) and "free" (no credit cost). Beyond that it says nothing about message ordering, pagination, thread-length limits, or what a 'complete thread' returns, which leaves meaningful behavioral gaps for a read tool.

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 compact sentences, front-loaded with the core purpose and followed by the key-sourcing prerequisite and safety/cost note. No redundant restatement of the name or title.

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?

No output schema and no annotations, so the description must do more. It covers `key` sourcing and cost/safety but leaves two required parameters (id, type) unexplained and gives no sense of the return shape or volume for a potentially large thread.

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 only 33%: only `key` is documented. The description usefully expands on `key` by naming its form (email address or LinkedIn chat id), but `id` and the required `type` enum are never mentioned in either schema or description, so the agent gets no guidance on those required inputs.

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: retrieve the complete message thread with one contact. This distinguishes it from the sibling crm_communication_history (which yields rows and the `key`), though the phrase "inside a card" is vague and adds little. An agent can identify the operation without opening the schema, but sibling differentiation is only implicit.

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?

Provides a useful prerequisite: `key` comes from a `crm_communication_history` row, implying this tool is used as a follow-up drill-down. However, there is no explicit when-to-use vs when-not guidance, and the id/type parameters are not framed as selection conditions.

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