Price Index — published API prices with sources

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

With no annotations, the description carries the full burden and does disclose a genuinely non-obvious behavior: it refuses to compare and returns comparable:false with a reason when a service publishes no monthly subscription. That is a valuable edge-case disclosure, though it says nothing about error handling for unknown or ambiguous service identifiers.

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 tight sentences with the primary behavior front-loaded and the failure mode immediately after. No 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?

Partial coverage: the failure mode and a return field (comparable:false) are noted, but with no output schema and no annotation support the description leaves the a/b identifier format, matching rules (exact vs fuzzy), and error cases unexplained.

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 0% and both parameters are opaque single letters (a, b). The description only says 'two services' and never clarifies that a and b are service identifiers, nor whether they are IDs, slugs, or names. It fails to compensate for the empty 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?

States a specific verb (compare) and resource (two services) scoped to the cheapest published monthly price, which clearly separates it from siblings like get_service_prices or get_cheapest_by_category. It stops short of explicitly naming an alternative, so it is clear but not sibling-differentiating.

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 comparison scope implies when to reach for this tool (pairwise comparison of exactly two services), but there is no explicit when-not guidance or named alternative against get_service_prices/get_cheapest_by_category. Usage must be inferred from the stated purpose.

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 full behavioral burden but discloses little. It does hint at the return shape ('source URL of each price') and implies a read-only aggregate, but says nothing about ordering, tie-breaking, currency, or what 'published' filters out.

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 front-loaded sentence with zero waste — verb, scope, and return content all in one line.

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 output schema exists, so the description must carry the return contract, and it only partially does: price + source URL are named, but the category set, currency, and result ordering are not. Adequate for a zero-param tool but leaves real 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 tool takes no parameters, so there is nothing for the description to disambiguate; baseline 4 applies. No parameter confusion is possible.

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+resource: 'Return the cheapest published monthly price per category' and adds the returned artifact (source URL). This clearly separates it from siblings like get_service_prices and compare_services, though it never names an alternative 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?

There is no guidance on when to use this tool versus get_service_prices or compare_services, nor any prerequisite or exclusion. The description only says what it returns, leaving selection entirely to 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, the description carries the full burden. It usefully discloses that the tool surfaces provenance (last vendor read) and scope limitations ('what it explicitly does not claim'), which is genuine behavioral context. However, it says nothing about access requirements, caching, or the shape of the response.

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 front-loaded sentence listing three return facets with no filler. It is efficient, though the comma-separated list structure is slightly dense rather than crisply segmented.

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 output schema exists, so the description must convey return content — it does so adequately by naming timestamps, coverage counts, and disclaimers. It is nearly complete for a zero-parameter metadata tool, missing only freshness semantics (e.g., what a stale timestamp implies).

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 of 4 applies; there is nothing for the description to disambiguate. The schema coverage is already 100%.

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 names the specific content of the report — vendor-page last-read timestamp, service coverage count, and explicit non-claims — which is a concrete read operation on an index resource. It is clear on its own, though it does not contrast itself against siblings like list_indexed_services or health_check.

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?

There is no statement of when to call this versus the other index-related tools, nor any prerequisite or timing guidance. The agent must infer that this is a freshness/provenance check rather than a data retrieval call.

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 provided, so the description carries the full burden. It usefully discloses the return payload (published plans, derived cost, source URL, read date), which is valuable given there is no output schema, but it says nothing about permissions, rate limits, caching, or freshness guarantees beyond the read date.

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 that front-loads the resource and then the return contents, with zero filler. 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?

For a simple one-parameter read tool with no annotations and no output schema, the description adequately covers purpose and expected return contents. It is only slightly short of complete because it omits any statement about the read-only nature or when to prefer a sibling 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% and the single 'slug' parameter already includes an example, so the schema does the heavy lifting. The description adds no additional slug format or resolution semantics beyond what the schema provides, making baseline 3 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?

States a specific verb (Get) and resource (published plans / USD-per-unit cost) scoped to 'one service', which implicitly contrasts with the multi-service siblings like compare_services and list_indexed_services. It is clear what the tool returns, though it never names an alternative sibling 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?

Usage is only implied via the phrase 'for one service', which signals single-service lookup rather than comparison or listing. There is no explicit when-to-use clause, no mention of alternatives like compare_services or get_cheapest_by_category, and no stated prerequisites.

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 provided, so the description must carry the behavioral load. It does disclose the payload semantics (up/down plus version) and is implicitly a safe, parameterless read, but it says nothing about latency, upstream dependencies, or whether a 'down' result includes an error reason.

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 sentence, front-loaded with the liveness answer and then the version detail. No filler, no restatement of the tool name.

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 annotations and no output schema, the description does the essential work of naming both return fields (status, version). It is nearly complete for a zero-param probe; only failure-mode detail (error string vs bare 'down') is missing.

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 per the rubric the baseline is 4; there is nothing for the description to disambiguate.

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 ('Report') plus the exact facts returned: liveness and answering version. None of the siblings (compare_services, get_service_prices, etc.) overlap with a liveness probe, so the agent can route to it unambiguously.

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?

Usage is implied by the nature of a health check, but the description never states when to call it (e.g., before a batch of price queries, on timeout/error) or that it is a prerequisite/diagnostic step rather than a data-fetching call.

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 provided, so the description carries the full behavioral burden. It usefully declares a strict data-provenance policy: 'No AI, no estimation - only values copied from vendor pages.' That is valuable trust context. However, it does not disclose key operational traits such as pagination, result size, rate limits, or whether missing prices are omitted. For a list tool with no annotations, this is adequate but incomplete.

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 tightly written sentences. The first front-loads what the tool returns, the second immediately states the provenance guarantee. There is no filler and every clause contributes relevant 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?

The description covers purpose, scope, and provenance, which is enough for an agent to understand what it will get. However, with no annotations and no output schema, it omits structural details an agent may need, such as the shape of returned records, pagination behavior, and error conditions. For a parameter-light list tool this is passable but leaves 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?

Schema coverage is 100% and the single optional category parameter is fully described in the schema with enum-like values. The description adds the semantic frame that the list covers OG-image, screenshot, and template services, reinforcing the category scope. Since zero parameters are required and schema coverage is complete, the baseline is already high; the description does not introduce syntax or format details 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?

States a clear verb and resource: list every OG-image, screenshot, and template service in the index with published prices and the page each price was read from. This is specific and distinguishes the tool as a comprehensive index lister. It does not explicitly differentiate from siblings like get_service_prices or get_cheapest_by_category, so it falls short of a 5.

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 the tool is for retrieving the full indexed catalog with source references, but gives no explicit when-to-use guidance, prerequisites, or alternatives. Siblings such as get_service_prices or compare_services are not mentioned, leaving the agent to infer that this is the broad enumeration tool.

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