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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, and the description adds meaningful behavioral context beyond those: it explicitly notes this lookup does not contact the business, and it discloses cost and latency. There is no contradiction with annotations.

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?

The description is well-structured and front-loaded: the core purpose appears first, followed by an example, usage conditions, non-usage conditions, and operational details. Every section earns its place and no wording is wasted or redundant with the schema.

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 low-complexity, read-only lookup tool with rich annotations, the description provides all needed context: what the tool returns, when to use it, when not to use it, an invocation example, cost, and latency. The lack of an output schema is adequately offset by the description's clear statement of what the lookup reveals.

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 carries the full burden for parameter meaning. It partially compensates through the example mapping ('smb_imp_abc' to smb_id and 'emergency_plumbing' to capability_to_verify), but it does not explicitly state that capability_to_verify is optional or what happens when it is omitted. Still, the example and context give the agent enough to select correct inputs in common cases.

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 and resource: 'Look up what we know about a business in our supply network,' and enumerates the record contents (contact channels, capabilities, last verified). It also clearly distinguishes itself by stating 'This is a DIRECTORY LOOKUP - it does not contact the business,' which separates it from any action-oriented sibling.

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 description provides explicit WHEN TO USE and WHEN NOT TO USE guidance, including the exact condition under which an alternative (find_business) should be preferred because results are already verified. The example user query with a direct tool call mapping makes the selection and invocation path unambiguous.

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