x402nano

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

With no annotations provided, the description carries the full burden. It mentions the cost and 'read-only' nature of the brief, but fails to disclose whether the purchase modifies state, is idempotent, requires authentication, or what the return value is. This is insufficient for a purchase action.

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 a single, concise sentence that starts with the verb 'Purchases', making it easily scannable. While it could include more detail, it avoids unnecessary words.

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?

Given the lack of output schema and annotations, the description should inform the agent about the return value or outcome of the purchase. It does not mention what the agent receives after purchase, leaving a significant 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?

The input schema covers 100% of the parameter with a description, so the baseline is 3. The description adds no additional meaning beyond the schema.

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 verb 'Purchases' and the resource 'read-only structured prediction-market brief', specifying cost and platform. It effectively distinguishes from sibling tools like get_market_delta or get_market_pricing, which are data retrieval tools.

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 no guidance on when to use this tool versus its siblings. It does not mention prerequisites, when not to use, or any usage context.

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?

The description discloses that the tool costs 0.05 USDC, which is a key behavioral trait. However, it lacks details on authentication requirements, rate limits, and what happens if the user has insufficient balance. Since no annotations are present, the description partially meets the burden.

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?

Single sentence front-loads the action ('purchases'), cost, and time requirement. It is concise with no wasted words, though splitting into two sentences could improve readability slightly.

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?

Missing critical details: the format of the returned report (e.g., list of changes, JSON structure), error handling (e.g., insufficient balance, invalid slug), and behavior for future timestamps. Without output schema, the description should provide more context for the agent to interpret results.

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% with both parameters having descriptions. The tool description merely reiterates the schema info ('since an ISO 8601 UTC timestamp' and 'Exact Polymarket market slug'), adding no new semantic value. Baseline score of 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?

Description clearly states it purchases a probability-change report for a market since a timestamp, specifying the cost. It distinguishes from siblings (get_market_brief, get_market_pricing, list_trending_markets) by being the only tool that provides a delta report and involves a payment.

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?

No explicit guidance on when to use this tool versus alternatives. It does not mention scenarios where one should prefer get_market_delta over get_market_brief or get_market_pricing, nor does it state when not to use it.

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 must disclose all behavioral traits. It states the tool returns data 'without making a payment', implying it is non-destructive, but does not discuss authentication, rate limits, or any side effects. For a zero-parameter query, the minimal behavioral disclosure is lacking.

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 a single, well-constructed sentence that efficiently conveys the purpose and scope. There is no redundant or extraneous information.

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?

Given the tool has no parameters, no output schema, and no annotations, the description provides a reasonably complete overview. It tells the agent what data it returns and that it does not require payment. However, it does not explain the meaning of 'MCP pricing' or the format of the output, which could be helpful.

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 tool has no parameters, so the schema coverage is 100% by default. The description adds value by enumerating the categories of returned metadata (pricing, network, asset, seller, payment), which the empty schema cannot convey.

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 specifies the verb (returns) and the resource (public MCP pricing, network, asset, seller, and payment metadata). It distinguishes itself from sibling tools by indicating this is the comprehensive pricing endpoint without any filtering or aggregation.

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?

No explicit guidance on when to use this tool versus its siblings (get_market_brief, get_market_delta, list_trending_markets). The description does not mention alternatives or provide context for selection.

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 must disclose behavior but only mentions 'free... candidates and slugs' without explaining the read-only nature, required authentication, rate limits, or what the output contains. Essential traits are missing.

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 very short (one sentence), but clarity is sacrificed. It is concise in length but not in effectiveness, as it fails to communicate clearly. Structure is simple but adequate.

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?

Given no output schema, the description should explain the return format but only vaguely mentions 'market candidates and slugs.' It does not cover how this feeds into sibling tools or what the output can be used for, leaving significant gaps.

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 'limit' is fully documented in the schema (100% coverage), so the description adds no extra meaning. The baseline of 3 is appropriate as the schema already handles parameter semantics.

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 'Lists free Polymarket market candidates and slugs before purchasing intelligence,' which is vague and conflicts with the title 'List trending prediction markets.' It's unclear what 'free' and 'before purchasing intelligence' mean, making the tool's purpose ambiguous.

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?

No guidance is provided on when to use this tool versus siblings like get_market_brief or get_market_delta. There is no mention of prerequisites, context, or exclusions, leaving the agent without decision support.

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