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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. With no output schema, the description adds real value by disclosing the returned fields (name, phone, status, AI summary, custom fields, assignee, pinned, contact_id, conversation_id). Auth/error behavior (404 not_found, 403) lives only in the schema, not the description.

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 filler: the purpose and returned-field inventory come first, and the id-sourcing instruction is placed last where it is needed. The field list is long but earns its place because no output schema exists.

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 two-parameter read tool with annotations covering safety and the schema covering errors, the description closes the only real gap by listing the returned fields in the absence of an output schema. Nothing an agent needs in order to call it correctly is missing.

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 100%, so both required parameters are fully documented in the schema, including the cross-agent 404 behavior. The description only implies the lead_id origin by pointing at list_leads and adds no format or scoping detail beyond the schema, so the baseline 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 ('Get one lead of an agent') and then enumerates exactly what is retrieved, so the agent knows the shape of the result without opening a schema. The closing pointer to list_leads as the source of the id cleanly separates it from list-family siblings.

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?

It tells the agent where the required lead_id comes from ('Get the lead's id from list_leads'), which is the key precondition for calling it. It gives no explicit when-not-to-use guidance (e.g. versus list_leads for bulk retrieval), so it falls short of a full 5.

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