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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), lowering the bar. The description still adds genuine context beyond them: partial-update semantics ('Only the fields you pass are changed; omit the rest') and the non-creation scope. It omits any mention of permissions or the return payload, keeping it short of a 5.

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?

Front-loaded with the routing constraint and scope before the core purpose, which is the right ordering. Slightly redundant: the first sentence's field list (e-mail, phone, position) is re-listed in the third sentence, a small amount of duplicated content.

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 full schema coverage and annotations covering safety and idempotency, the description supplies the remaining needed context: partial-update behavior and the create-vs-update boundary. No output schema exists, but for a fire-and-forget partial-update tool the omission of return details is minor.

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%, so every parameter is already documented in the schema. The description's field list mirrors the schema rather than adding format, validation, or coupling details (e.g. how 'contact_id' resolves). Baseline 3 is appropriate when the schema does the heavy lifting.

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 ('Update a lead's contact details') and enumerates the exact editable fields (email, phone, location, company, position, headline). It explicitly distinguishes itself from two named siblings (set_deal_stage, set_lead_fields), so an agent can route without inspecting other schemas.

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 explicit when-to-use ('Use to enrich a lead, e.g. save an email address you found') and when-not-to-use with named alternatives for pipeline stage and custom fields. The 'Does not create contacts' exclusion closes the remaining ambiguity about scope.

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