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

Annotations already declare readOnlyHint=false, destructiveHint=true and idempotentHint=true; the description adds the genuinely useful behavioral fact that this is a partial PATCH — fields not passed retain their values — which the annotations cannot express. It does not explain why destructiveHint is set for a contact edit (e.g. overwrite risk) or any auth/permission requirement, leaving a small gap.

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 dense sentences, front-loaded with the WRITE marker and the partial-update guarantee, then exclusions, then the endpoint. No filler and every clause carries information an agent needs.

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 14-parameter PATCH with no output schema and only partial-update semantics at stake, the description covers field scope, exclusions, and HTTP semantics sufficiently to call it correctly. It omits only the response shape and validation/failure behavior, which is acceptable given no output schema exists.

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 21%, so the description must carry weight, and it does: 'name, title, email, phone, address, company' maps onto all 13 optional properties (first/middle/last_name, title, email_address, phone/phone_ext, address1/address2/city/state_code/zip_code, contractor_company). The remaining schema descriptions cover contractor_id semantics, so only format-level details (state_code two-letter, email pattern) rely on the 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?

Opens with an explicit write verb and resource ('WRITE: changes... contractor contact fields') and pins the endpoint (PATCH /v1/Users/contractors/{contractorId}). The scope statement makes it trivially distinguishable from bilflo_update_client and bilflo_update_contract_job despite the shared 'update_*' naming pattern.

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 clear positive condition (use this for contact details) and an explicit exclusion list (tax, bank, SSN, activation are not changeable here), which prevents misfires. It stops short of naming the sibling tool that should be used for those excluded fields, so the agent must infer the redirect.

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