PayAPI Market

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

With no annotations, the description carries the full burden of behavioral disclosure, and it does so thoroughly. It states the operation is read-only, 'spends nothing', returns listings regardless of verification, and honestly reports payment_verified. It also explains what the reliability score means and what it does not mean, which is valuable beyond schema information.

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 front-loaded with the core purpose and remains information-dense. Most sentences add meaningful context about reliability, verification, and cost. The 'Method: URL' clause feels slightly extraneous and the reliability explanation is lengthy, but everything is relevant enough that it stays within reasonable bounds.

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?

Despite having no output schema, the description enumerates the returned fields, including the nested reliability object with its possible values and meaning. It covers edge cases like unverified listings and unscored reliability, and the parameter provenance ties cleanly to sibling tools. An agent has enough to call this correctly.

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?

There is only one parameter and schema description coverage is 100%, so the schema already fully documents 'id' as 'Listing uuid or slug, as returned by search_apis or list_apis'. The description repeats this same meaning without adding new format, constraints, or examples, so the 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?

The description opens with a specific verb and resource: 'Fetch a single live listing by its id or slug'. It differentiates from sibling tools by emphasizing 'single' retrieval versus listing/search, and even names the source of the id ('as returned by search_apis or list_apis').

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 this tool is for fetching one listing by id or slug, and it notes where those identifiers come from ('as returned by search_apis or list_apis'). It does not explicitly spell out when not to use it or contrast it with alternatives, but the single-vs-many distinction gives clear contextual guidance.

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 and discloses key behavioral traits: the operation is 'Free and read-only; spends nothing' and only returns settlement-verified listings unless told otherwise. This is valuable context beyond the schema. It doesn't mention pagination or rate limits, but the essential safety and filtering behavior is covered.

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?

Three concise sentences, front-loaded with the core purpose. Every sentence adds information: browse behavior, category handling, verified filtering, and cost/safety. There is no filler or 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?

For a simple listing tool with three optional parameters and no output schema, the description covers the main usage, filter semantics, and side-effect profile. Missing guidance is limited to sibling routing and pagination details, and those are partially implied by the schema constraints.

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 low (33%), and the description compensates for category and verified_only: it defines the category filter ('Omit category for everything') and the verified_only default behavior. However, the 'limit' parameter is never described in either the schema or the description, leaving a small but real gap.

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 clearly states the operation: browsing/listing the live catalogue, optionally filtered by category. It uses a specific verb and resource. It distinguishes itself from get_api and search_apis by the notion of browsing the full catalogue, though it does not name the siblings explicitly.

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 provides direct usage guidance: 'Omit category for everything' tells when to skip the filter, and 'Returns settlement-verified listings only unless verified_only is false' explains the default behavior. It also notes the tool is free and read-only, signaling safe use. It doesn't explicitly say when to prefer search_apis or get_api, but the context is 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?

With no annotations, the description carries the disclosure burden. It explicitly states the operation is read-only, free, and spends nothing, and it explains the verified-only filtering behavior. This goes well beyond the schema.

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?

Three compact, information-dense sentences. The core purpose is front-loaded, and every sentence adds operational value without fluff.

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?

Adequate for a read-only search tool. It covers what is searched, the filtering default, and the safety profile. It does not describe the return shape, but the absence of an output schema is a minor gap for a simple search result list.

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 description clarifies what the query parameter matches (listing name, description, category, provider name) and confirms how verified_only changes results, supplementing the schema. Limit is not described, but its schema constraints make it self-explanatory.

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 ('search'), resource ('live catalogue'), and searchable fields (name, description, category, provider name). Clearly distinguishes itself from siblings: this is free-text search, not retrieval of one API or a plain list.

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?

Makes the intended use obvious: free-text queries over the catalogue. It does not explicitly name get_api/list_apis as alternatives, but the framing is clear enough that an agent can select it appropriately for keyword-style lookups.

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