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

Annotations already cover read-only, open-world, idempotent and non-destructive, yet the description adds real substance: costs, the payment_url two-step flow, refusal without charge if a control fails, citation lines with run id and date, and the publish-to-cultmath.com path. The caveat is internal muddle: 'This tool charges nothing' sits alongside 'Price: $0.05 per run' and 'charged only when the run comes back sound', and two separate payment rails (x402 and MPP) are offered without saying which an agent should pick.

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 use case is front-loaded well, but everything after it is one dense paragraph that mixes purpose, payment rails, pricing, publication policy, trust claims and a sample URL. Marketing-flavoured lines like 'Safe to cite' and the free-sample link compete with operational detail an agent needs at call time. Some sentences, such as the pricing restatement, repeat themselves.

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?

There is no output schema, so the description carries the return burden and does so: class shares, class leaders, top three, 'domains and counts only'. Failure and billing behaviour are covered. What is left unclear is whether an agent must make a second POST after paying and how the x402 versus MPP choice is made, which matters for a tool whose call is not a single round trip.

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 the baseline is 3, but the description earns extra by explaining why the domain-list parameters exist: results are classified as retailers and marketplaces, reviews and media, brand sites, forums and social, reference, and independent or specialist sites, so passing brand_domains, media_domains or retailer_domains corrects misclassification. It also restates the 1-3 query bound in prose. No syntax detail beyond the schema is added.

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: it searches Google live for 1-3 buyer queries and classes every top-10 organic result by domain type, returning class shares, class leaders, and top-three occupiers. That is far more concrete than the title alone, which is only a question. It does not explicitly contrast itself with near-siblings such as run_share_of_search, so an agent must infer the difference.

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 a clear trigger: use when the user is planning go-to-market or channel strategy and asks where buyers look, whether to prioritise retail, review sites, their own site, or communities. That is a well-specified use context. There is no explicit when-not-to-use condition and no sibling is named as the alternative, which keeps it short of a 5.

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