CPFHub.io

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

With no annotations, the description carries the full burden. It discloses the key behavioral fact that authentication via API key is required and characterizes the data as a public read set, but says nothing about rate limits, error behavior, or whether the call has side effects. Adequate but incomplete for a tool with zero annotation coverage.

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 sentences with zero filler. The data-scope statement is front-loaded and the auth requirement follows immediately; nothing could be trimmed without losing 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?

There is no output schema, so the description must summarize returns, which it does by naming the data set (credit balance and plan). For a one-parameter, read-only quota tool this is nearly complete, with only return-format or pagination detail 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?

Schema description coverage is 100% and the single api_key parameter is fully documented in the schema, including that it is optional if already supplied via the x-api-key header. The description only restates the auth requirement, adding no syntax or format detail 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 specific verb and resource: returns credit balance and plan data. It is clearly distinct from the sibling CPF lookup tools, though it does not explicitly name them to reinforce the distinction. A precise endpoint equivalence (GET /quota) anchors the purpose.

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 use case (checking balance/plan) but never states when to call it versus the lookup_cpf siblings, nor any preconditions beyond auth. The endpoint equivalence gives indirect context but no explicit when/when-not 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?

No annotations are provided, so the description carries the full burden. It usefully discloses the auth requirement (API key via x-api-key) and the shape of the return data, which is valuable given there is no output schema. It says nothing about rate limits, cost, error behavior, or data freshness relative to the realtime sibling.

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 purpose, then the return values, then the auth requirement. No filler and nothing redundant.

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 low-complexity two-parameter tool with no output schema, the description covers purpose, return fields, and auth. The one material gap is the failure to differentiate from lookup_cpf_realtime, which an agent would need in order to choose 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?

Schema description coverage is 100%, so both parameters are already fully documented in the schema, including the accepted CPF formats and the optional-header fallback for api_key. The description adds no syntax or format detail beyond the schema, 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 ('Consulta informações de um CPF brasileiro na CPFHub.io') and enumerates the returned fields (nome, data de nascimento, gênero). However, it does nothing to distinguish itself from the sibling 'lookup_cpf_realtime', which strongly implies a cached/database vs. real-time distinction that the description never addresses.

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 when-to-use guidance is given. The presence of 'lookup_cpf_realtime' as a sibling makes the missing selection criteria a real problem — an agent cannot tell which CPF lookup to pick. The description only notes that an API key is required, which is a prerequisite, not usage 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, the description carries the disclosure burden and does unusually well: it names two error conditions and codes, states those errors incur no credit charge, requires API-key auth, and notes deathYear is always present (number | null). It omits rate limits, latency/timeout behavior, and whether success consumes credits, so it is not complete.

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?

Four tightly packed sentences with the core purpose front-loaded, then return shape, error behavior, and requirements. No filler, though it is dense enough that the return-shape and error details momentarily crowd out the primary action.

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?

There is no output schema and no annotations, so the description must carry return semantics — and it does describe the payload (cadastral data, current situação, always-present deathYear) and error codes. The main remaining gap is no guidance on distinguishing this tool from its sibling lookup_cpf.

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 cpf, birth_date formats, and the optional x-api-key alternative are already documented in the schema — baseline 3. The description adds only the consequence of a birth_date mismatch, not new syntax or defaults.

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 ('Consulta um CPF brasileiro') plus scope and source ('em tempo real na Receita Federal pela CPFHub.io'). The 'tempo real' qualifier implicitly separates it from the sibling lookup_cpf, but the description never names that sibling, so an agent must infer which lookup 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?

Usage is only implied: 'em tempo real' suggests this is the live/authoritative variant versus the cached lookup_cpf, but there is no explicit when-to-use, when-not-to-use, or cost/latency tradeoff guidance for choosing between the two lookups. Prerequisites (CPF, birth_date, API key) are stated, which helps.

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