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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description still adds real value by disclosing partial-update semantics (unspecified fields are untouched) despite the PUT verb, which would otherwise imply full replacement. It does not warn that background text is overwritten, but the schema parameter description covers that.

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?

Three short sentences, zero filler, and the most important signal (WRITE) is front-loaded before the behavioral nuance and the endpoint.

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 small mutation tool whose annotations already carry the safety profile, the description plus schema covers what an agent needs to call it correctly. The only gap is that it doesn't say what the call returns, though the absence of an output schema makes that a minor omission.

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 the baseline would be 3, but the line "Only the fields you give are sent" adds meaning the schema does not: optional parameters are omitted rather than cleared. That materially changes how an agent constructs the call.

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?

"WRITE: change fields of a company" names a specific verb and resource, and the resource name distinguishes it from update_deal/update_person/update_task siblings. It doesn't explicitly say to use create_company for new records or get_company for reading, but the verb+resource pairing is unambiguous.

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?

Usage is implied by the WRITE marker and the "Only the fields you give are sent" clause, which hints at partial-update intent. However, it never names an alternative (create_company, get_company) or states preconditions such as needing an existing company_id.

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