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

Annotations already declare readOnlyHint=true, so the safety profile is covered; the description adds value beyond them by disclosing the payload contents, the multi-location behavior of the locations field, and the cost/latency signal ('cheap'). It doesn't mention auth failure modes or rate limits, keeping it at a solid 4 rather than 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-loads the operation and its return contract, then the usage hint, with no filler. The trailing 'Housecall Pro: GET /company' is endpoint trivia that is only marginally useful for an agent, costing it the top mark.

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 no output schema, the description carries the burden of describing returns and does so by enumerating the fields, including the conditional locations array. Complete enough to call correctly; only the absence of any error/empty-response guidance keeps it from a 5.

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?

The tool takes zero parameters, so parameter semantics carry a baseline of 4 by rule. The description correctly adds no param prose, and the key-scoping ('this key belongs to') explains implicitly how the target company is determined.

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?

Specific verb+resource ('Fetch the Housecall Pro company this key belongs to') plus an enumeration of exactly what comes back (name, contact details, address, time zone, service-area zip codes, locations). The scope phrase 'this key belongs to' cleanly separates it from sibling getters like housecall_get_customer and housecall_get_job, which take an ID.

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 one concrete use case — 'A cheap way to confirm the key works' — which tells an agent when this is the right call (credential/connectivity validation) rather than one of the list_* tools. It stops short of naming alternatives or stating when not to use it, so it lands just below the explicit-routing bar.

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