Receipts Index

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

The annotations already declare readOnlyHint=true and openWorldHint=true, but the description adds substantial behavioral context: the call is free, returns only ids/dates/counts, does not return row content, and row content is sold separately through x402. This is exactly the kind of cost and output-scope disclosure an agent needs 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?

The description is front-loaded with the endpoint and free status, then the return shape, pagination, and the paid-content limitation. Every sentence adds relevant information with no padding.

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 read-only index tool with no output schema, the description covers the return fields, the absence of row content, pagination, and the paid-content boundary. An agent has enough information to call it correctly and understand what it will and will not receive.

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 schema already explains that limit is rows per page (1-500) and start is the first row id. The description adds only that these parameters page through row ids, which is useful but not meaningfully 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 gives a specific endpoint, scope, and return contents: GET /v1/index, free row ids and UTC dates without row content, row count, first/last dates, and dates with rows. It also explicitly distinguishes this from paid row-content retrieval, so an agent can identify it as a metadata-index tool rather than a content or pricing tool.

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?

It clearly states that start and limit are used to page through row ids and that row content is not returned here, which gives useful context for when this tool fits. However, it does not name sibling tools like receipts_sample or receipts_pricing or explicitly route the agent to them for row content or pricing.

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; the description adds real value beyond them by disclosing cost ('Free to call') and side-effect boundaries ('never pays and never signs anything'). It doesn't mention rate limits or what happens if the well-known route is unavailable, so a small gap remains.

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 short sentences, front-loaded with what it reads and what it returns, followed by cost and safety guarantees. Every sentence carries distinct, useful information with no repetition of the title.

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 must convey the return: it does ('paid endpoints with their prices in USDC'). It omits the response shape (e.g., mapping of route to price) and pagination/error behavior, but for a simple manifest read this is close to sufficient.

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 takes zero parameters, so there is nothing for the description to disambiguate; the description correctly signals a no-argument call. Baseline 4 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 ('Reads GET /.well-known/x402 ... returns the paid endpoints with their prices in USDC') and names the upstream sources. It does not, however, differentiate itself from the similarly named sibling receipts_index, leaving some ambiguity about which index tool to pick.

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?

Clearly frames this as a discovery/pricing lookup ('Free to call') and explicitly redirects the actual payment step elsewhere ('Paying is done by an x402 client against the listed route'). No explicit when-not or comparison to receipts_index/receipts_sample, but the intended context is unambiguous.

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 cover the safety profile (readOnlyHint=true, openWorldHint=true), yet the description still adds real value: it declares the tool is free, takes no parameters, hits a live external endpoint, and explicitly is not a purchase — preempting the obvious billing concern. It doesn't mention rate limits or auth, which keeps it below 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?

Three short sentences, front-loaded with the endpoint, then the return payload, then the no-param/no-purchase guarantees. No filler and nothing repeated twice.

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 carries the return-value burden and does so concretely (row id, paid route, price, fields and CSV). The absence of any auth or rate-limit context for an open-world external call is the remaining gap, but for a free, parameterless sample endpoint it is close to complete.

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 takes zero parameters, so the baseline is 4. The description correctly states "It takes no parameters," which is redundant with the empty schema but harmless and confirms the constraint.

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 ("Calls GET /v1/sample on the Receipts API") and enumerates exactly what comes back: row id, paid route, price, fields and CSV. It implies this is a preview rather than a paid fetch, but never names receipts_index or receipts_pricing, so sibling differentiation is left to inference.

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?

"Free" and "not a purchase" tell the agent this is a no-cost preview, which is useful implied guidance, but there is no explicit statement of when to choose this over receipts_index or receipts_pricing. The usage is inferable rather than stated.

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