Agent Deals

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful behavioral context: the service is FREE, covers roughly 25,000 APIs, and is re-checked continuously, which informs the agent about cost and data freshness.

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 description is two sentences, front-loaded with the most important fact ('FREE. Before paying...'), and every phrase earns its place. It avoids repetition and unnecessary detail.

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 two-parameter tool with no output schema, the description communicates what the tool checks, when to use it, and its coverage. The exact return format is not specified, but the three checks imply the result categories well enough for an agent to invoke and interpret the tool.

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 both parameters (url and method) are already documented. The description adds no additional parameter-level meaning, which is acceptable given the complete schema. Baseline of 3 applies.

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?

Description names a specific verb ('check'), a resource ('x402 service'), and three concrete checks: uptime, price match, and cheaper alternatives. This clearly differentiates it from sibling 'find_cheapest_x402_service', which is about discovery rather than verification of a specific URL.

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 explicitly states the usage trigger: 'Before paying an x402 API, check it.' This gives clear context for when to call the tool. It does not explicitly mention when not to use it or name alternatives, but the trigger is sufficiently clear.

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

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

Beyond the readOnlyHint and openWorldHint annotations, the description adds meaningful behavioral details: results are ranked by live price, uptime, and speed, include example inputs, and there is a free tier followed by a per-call fee via x402. This gives the agent practical expectations about cost and output ordering.

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 description is two sentences with no filler. It front-loads the core instruction ('Describe what you need'), states the result and ranking criteria, and then gives essential pricing information. Every clause earns its place.

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?

The description is complete enough for a search/discovery tool: it explains the input, output ranking, and cost model. It does not describe a return format, but it names the key output dimensions and there is no output schema to satisfy, so this is a minor gap.

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 the schema already documents all three parameters. The description adds context about paid APIs and pricing that helps interpret max_price_usd, but it does not add new semantic detail beyond what the schema provides, so the baseline score of 3 applies.

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: 'find the cheapest WORKING paid APIs' for a described task. It clearly conveys the tool's discovery function and distinguishes it from the sibling tools like check_x402_service, which likely verify a specific service rather than search for one.

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 clearly implies when to use this tool: when you need to find the cheapest working paid API for a task, with the user describing their need in plain words. It does not explicitly state exclusions or alternatives, but the context and phrasing make the intended use clear.

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

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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the read-only, network-access safety profile. The description adds useful context about the target being a public page and the $0.002 per-call cost via x402. It does not disclose potential failure modes (e.g., blocked pages, missing metadata fields) but adds meaningful context beyond the annotations.

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?

A single sentence efficiently lists the output fields, followed by the pricing detail. No filler or redundant phrasing, and the most important content (what the tool returns) is front-loaded.

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 simple one-parameter, read-only tool with annotations and no output schema, the description adequately lists all returned metadata fields and the cost. It lacks details on edge cases like pages with missing metadata or scraping restrictions, but the core behavior an agent needs to invoke the tool correctly is present.

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?

The only parameter, url, is fully described in the schema (format: uri, description: 'Public http(s) URL'). The description adds no additional parameter semantics, but with 100% schema coverage, the schema already carries the burden, so 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?

The description enumerates the specific metadata fields returned (title, description, canonical URL, language, site name, author, publish date, image, JSON-LD) with a clear verb 'get' and precise resource. This distinguishes it from the sibling read_web_page, which likely returns page content, without needing to inspect schemas.

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 usage for metadata-only extraction from public pages and notes the cost, but it does not explicitly state when to use this tool over read_web_page or the x402 service tools, nor does it provide exclusions or conditions for selecting an alternative.

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

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

Annotations only declare readOnlyHint and openWorldHint; the description adds genuinely new context: the tool is free, it evaluates live service health, price fairness versus public listings/monitor data/similar services, and wallet safety versus the wallet the service normally uses. It also discloses the verdict vocabulary returned. It does not mention latency, failure modes, or behavior when data is unavailable.

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-loads the two most decision-relevant facts (FREE, run before paying) and then enumerates the return semantics. The long parenthetical question in the final sentence is slightly run-on but every clause carries information rather than filler.

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 compensates by describing the GO/CAUTION/STOP result and the dimensions evaluated. Combined with a fully documented 6-parameter schema, an agent has enough to invoke and interpret the tool, though details of each verdict's reasons remain unspecified.

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 adds relational semantics: url and payment_required are alternatives, and price_usd/pay_to are the fallback when the header is not available. It also frames max_price_usd's behavioral effect as an optional STOP threshold.

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 (preflight/check) on a specific resource (an x402 service before payment) and explains the output (GO / CAUTION / STOP). An agent can immediately tell this is a pre-payment safety gate rather than a discovery tool like find_cheapest_x402_service.

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?

"Run this before paying any x402 (HTTP 402) service" gives an explicit trigger condition, and the description of what to pass (URL + PAYMENT-REQUIRED, or price_usd/pay_to) clarifies the input path. It does not explicitly name when to prefer the sibling check_x402_service instead, so it stops short of full alternative routing.

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

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

Annotations already declare readOnlyHint and openWorldHint, so the description only needs to add context. It adds useful behavioral details: output includes clean Markdown plus metadata fields, pricing via x402, and that failed reads are not charged. No annotation contradiction exists.

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 sentences deliver purpose, output contents, pricing, and failure billing without wasted words. The core function is front-loaded, and pricing/failure policy is placed as a compact second sentence.

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?

With no output schema, the description adequately names the return payload (Markdown plus title, author, date, JSON-LD, links) and notes cost/failure behavior. It could mention error handling or redirect behavior, but for a read-only fetch tool the provided context is sufficient for a likely-correct 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 description coverage is 100%, so the schema already explains url, selector, and max_chars. The description does not need to restate parameters and adds no extra per-parameter semantics, landing at the baseline for fully documented 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?

The description states a specific verb ('Fetch') and resource ('a public web page or PDF') and clearly promises clean Markdown plus title, author, date, JSON-LD, and links. This differentiates it from the metadata-only sibling get_page_metadata and from the x402 service-check siblings.

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 makes clear this tool is for public web pages/PDFs and that failed reads are not charged, giving an agent a good sense of when it applies. It does not explicitly name alternative tools or exclusion conditions, but the context is clear enough for selection.

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