P0 Agent Economy Index

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

With no annotations, the description carries the full burden. It usefully clarifies that listing is free but 'the data itself is paid per call over x402 at that URL,' and scopes the email check to 'syntax and MX, no mailbox probe.' However, it omits auth requirements, rate limits, and return format details.

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?

Purpose is front-loaded in a single sentence with the payment model called out at the end. The long parenthetical product enumeration is dense but each item conveys real availability information, so it 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?

For a discovery tool with one optional parameter and no output schema, the description covers what is returned (route, price, parameters, example request URL) and the payment mechanism. Only authentication/pagination context is absent, which is minor for a public catalog.

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% and the single 'route' parameter is already documented as optional with an example ('/weather'). The description adds no format or filtering semantics beyond that, so the baseline 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?

States a specific verb and resource ('List the paid data products on this host') and enumerates the concrete product categories, so an agent knows exactly what it gets. It does not explicitly name or distinguish itself from the sibling search_x402_services, so it falls short of full sibling differentiation.

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 never states when to use this tool versus search_x402_services or x402_market_stats, nor any when-not conditions. Usage is only weakly implied by the enumeration of products, leaving routing to the agent's inference.

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?

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals ranking methodology ('unique payers weighted above raw call volume'), scope ('every service in the public index'), and access limits ('Free tier returns the top 5; full results... available as paid endpoints'). This is strong, specific behavioral transparency.

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 core purpose and key behavior are front-loaded in the first sentence. Subsequent sentences add valuable context about scope and limitations. The final sentence about a weekly report is tangential to invoking the tool, causing a slight deduction.

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 two-parameter search tool with no output schema and no annotations, the description is quite complete: purpose, ranking, coverage, and rate limits are covered. It does not describe the result format, but the search intent and limits make this acceptable.

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 baseline is 3. The description does not add meaning beyond the schema; it only reiterates the capability search concept already captured by the query parameter description.

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 ('Search') and resource ('live x402 services') with a clear scope ('by capability' and 'Covers every service in the public index'). It does not explicitly distinguish from the sibling x402_market_stats, but the purpose is unambiguous.

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 establishes the intended use case: searching services by capability, with ranking context. It does not explicitly mention alternatives or when not to use the tool, but the scope and capability focus provide clear context. Absence of sibling differentiation keeps it from a 5.

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?

No annotations are present, so the description carries the behavioral burden. It is clearly read-only in nature (

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?

One dense sentence that enumerates the returned statistics and clearly states the tool's scope. No filler, no 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?

No parameters, no annotations, no output schema, but the description lists the key fields returnedholistically and matches the tool name. What's missing? not much; expected return values are literally enumerated.

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?

Tool has 0 parametersais schema coverage 100%? Actually no properties. With zero params, baseline 4. Description compensates by telling agent exactly what the output contains (catalog size, median price, 30-day calls, unique payers, categories). It doesn't need to explain any params.

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 clear verb (statistics of market) with a specific subject (x402 service market) and enumerates the concrete metrics returned: catalog size, median price, total 30-day calls, unique payers, and top categories. This distinguishes it from the sibling search_x402_services, which presumably searches individual services rather than aggregating market-level stats.

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 frames this as a market-level statistics endpoint, so an agent can infer when to call it (when aggregate market numbers are needed). However, it never explicitly contrasts it with the sibling search_x402_services or states when *not* to use it, leaving the routing decision to inference.

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