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

With readOnlyHint/openWorldHint already covering safety, the description adds substantial non-structured behavior: page scope (homepage + up to 3 pages), the credit cost model (1 per page, max 5), that credits are held and unused ones refunded, and that failed calls are free. This is exactly the operational context annotations cannot express.

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-loaded with the core action and scope, followed by one dense cost sentence. Slightly long in the field-list clause, but every sentence carries information the agent needs.

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 read-only tool with no output schema, the description names the returned fields and discloses page limits, cost, refund, and failure behavior, so nothing critical is missing for correct invocation.

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 100%, so both domain and idempotency_key are documented in the schema. The description adds no parameter-level detail (it does not mention idempotency/retry behavior beyond what the schema states), so the baseline 3 is appropriate.

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 (read/profile) and resource (company domain/homepage + standard pages) and enumerates the returned fields. It is clearly distinct from siblings like extract_contacts or extract_products because it returns a whole company profile rather than one field class.

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 implies when the tool applies (you have a domain and want a broad company profile) but never names alternatives such as extract_contacts or scrape, nor states when not to use it. Usage is inferable but not explicit.

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