Web search API for AI agents (SERP, no API key): ranked results (title, URL, domain, snippet, position) for any query, with region (us, uk, de, fr, es, ...) and time filter (day, week, month, year). Up to 10 results per call. Price: $0.003 per call (x402, USDC).
| Name | Required | Description | Default |
|---|---|---|---|
| q | Yes | Search query | |
| time | No | day, week, month or year | |
| limit | No | ||
| region | No | us, uk, de, fr, es, ... |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does well: it discloses the auth model (no API key), the pricing and payment rail ($0.003 per call via x402 in USDC), and the result cap (up to 10 per call). It omits rate limits and error/failure behavior, which keeps it short of a 5.
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?
Two dense sentences, zero filler, with the core capability, return fields, filters, cap, and cost all front-loaded in the order an agent needs them. Nothing is repeated and nothing extraneous is included.
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?
No output schema exists, and the description compensates by enumerating the returned fields, plus it covers cost and the result cap. Only operational details like error handling and rate limits are absent, which is a minor gap for a paid search call.
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 75%, so the schema already documents q, time, and region; the description's main added value is clarifying that limit is capped at 10 results per call, and it repeats the region/time value lists. It adds some meaning but not enough to exceed the baseline for high-coverage schemas.
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 and resource ('Web search API') plus the exact return shape (title, URL, domain, snippet, position) and scope ('any query'). It is clear what the tool does, but it never names or distinguishes itself from siblings like web_fetch, web_read, or web_search_read, leaving that inference to the agent.
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?
Usage is only implied by the query-centric framing; there is no explicit statement of when to prefer this over web_search_read or web_fetch, nor any exclusions. The mention of 'no API key' and region/time filters hints at context but does not route the agent between alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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