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

Annotations already provide readOnlyHint=false, idempotentHint=true, and destructiveHint=true, so the description does not need to restate the mutation safety profile. It adds the useful prerequisite that the write-tools skill must be read first, but it does not clarify overwrite/merge semantics for omitted fields.

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 sentences, action first, with no filler. The skill prerequisite is a necessary operational instruction and 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?

The definition covers the prerequisite and basic purpose, but for a mutation tool with destructiveHint=true and no output schema it stays minimal: it omits update semantics, alternative routing, and any mention of what happens to values not supplied. It is adequate for a simple schema but not fully complete.

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?

With 0% schema description coverage, the description should compensate by explaining the companies array, the required companyId, and field update semantics; it only adds 'one or more existing companies,' which the schema's minItems/maxItems already conveys. The nested connections and optional fields are left entirely to 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?

The description uses a specific verb ('update') and resource ('existing companies'), which makes the core action clear and separates it from create/merge siblings. It does not explicitly name or contrast any sibling, so it stops short of full differentiation.

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?

The phrase 'existing companies' implies this is for modifying already-created records rather than creating or merging, and the skill-reading instruction provides a clear prerequisite for use. However, it does not explicitly state when to prefer this over update_people, merge_companies, or other alternatives.

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