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

Annotations only carry title and destructiveHint=true, so the description must add behavioral context – and it does, via partial-update semantics and the concrete PATCH endpoint. It says nothing about reversibility, permission requirements, or that custom fields must be routed through the 'extra' passthrough, which are material for a mutation.

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 front-loaded sentences, no filler, and the partial-update rule appears before the API detail. Every sentence earns its place.

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 9-param destructive mutation with no output schema, the description covers purpose, update semantics, and endpoint, and the 100%-covered schema handles field-level detail. The main omission is signaling that non-schema/custom fields go through 'extra'.

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 the baseline is 3. The description adds only the partial-update rule; it does not explain the 'extra' passthrough or the link-flattening behavior that the schema itself describes.

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 fields on an existing company') and the word 'existing' separates it from twenty_create_company. It stops short of naming a sibling alternative or clarifying overlap with twenty_list/get tools, but the purpose 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?

'Only provided fields change' tells the agent this is a partial/PATCH-style update rather than a full replace, which is a genuine usage cue. However, there is no explicit when-to-use guidance, no prerequisite/permission note, and no mention of how to add fields not in the schema.

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