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

Annotations only cover the safety profile (read-only, open-world, idempotent); the description adds the material behavior they cannot express: a per-call price, the x402 payment handshake, and the two-step pattern where this tool returns payment instructions rather than the brief itself. Those are exactly the traits that would otherwise cause a failed invocation.

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 payload is packed into essentially two sentences, with the what-is-it clause first, then pricing/payment, then 'Read-only.' Front-loading is good and there is little waste. The trailing 'Read-only.' largely duplicates readOnlyHint/destructiveHint annotations, a minor redundancy.

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?

An output schema exists, so return-value detail is unnecessary, and the description covers the remaining gaps: contents of the brief, source provenance (public sources with URLs), cost, and the mechanism for actually obtaining the brief. Nothing an agent needs to call this correctly is missing.

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 description coverage is 100%, so company and domain are already documented in the schema, including the 'no https' format and the crawl benefit of domain. The description adds no parameter-level meaning of its own, which is the expected baseline when the schema does the heavy lifting.

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?

It names a specific resource (a sales prospect brief for one company) and enumerates exactly what it contains: overview, positioning, likely needs and talking points, from public sources with URLs. That is far more informative than the sibling lookups. It stops short of a 5 only because it never explicitly contrasts itself with basic_lookup/enriched_lookup, which the agent must infer is the cheaper alternative.

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?

It gives decisive operational context: the call costs $3.00 USDC on Base via x402, this MCP call returns payment instructions, and the actual brief is fetched via POST /v1/deep. That is the critical 'how to use' flow an agent needs. It does not state when to prefer this over the cheaper sibling lookups, so it falls short of explicit when/when-not guidance.

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