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

Beyond the annotations (readOnly, idempotent, non-destructive, closed-world), it discloses that no credits are consumed, that no discovery is triggered, the breadth of the payload returned, and that an undiscovered domain yields a structured `not_found` status rather than an error. That last point materially changes how an agent should handle a failure case.

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 tight sentences with the core purpose front-loaded, followed by output scope and cost/negative behavior. No filler and nothing repeated from the annotations.

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 single-parameter read with an output schema already present, this covers selection context, cost, output breadth, and the not-found path — everything an agent needs to call it and interpret results correctly.

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 0% and `domain` is an undescribed string, so the description carries the burden; it clarifies that the value must be a domain already surfaced by discovery (a `found[]` entry). It does not give a format example or explain normalization, which leaves a small ambiguity about accepted input shape.

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 ('Fetch') and resource ('FULL record for one already-discovered company by its domain'), and explicitly contrasts the output with the lean `search_prospects` summary. An agent can distinguish this from `find_prospects`, `search_prospects`, and `get_discovery_results` without opening any schema.

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 clear selection context: use it to expand a `search_prospects` summary or a `found[]` domain, and warns that it does not run new discovery (routing that intent elsewhere). It stops short of a full when-not list naming the sibling tools to use for fresh discovery, so it is strong but not exhaustive.

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