Ziptax Sales Tax API

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

Annotations already establish readOnly, idempotent, non-destructive, and closed-world behavior, so the safety profile is covered. The description adds genuinely new operational context beyond the annotations: the exact auth mechanism (X-API-KEY or Authorization header) and where to obtain a key. It does not describe response shape, rate limits on the metrics endpoint itself, or pagination.

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 short sentences, front-loaded with the purpose before the auth mechanics and key-acquisition link. Every sentence carries information; the key URL is the only marginally expendable element.

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 zero-parameter, read-only tool with rich annotations, the description covers purpose, return contents, and auth prerequisites. With no output schema present it would have been stronger to sketch the response fields or units (e.g., period covered), but nothing critical to correct invocation 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 clarify beyond the empty schema, and it does not introduce confusion about inputs.

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 a specific verb and resource ('Get account usage metrics and quota information for the authenticated ZipTax account') and enumerates what comes back (request counts, limits, entitlements). It never mentions the sibling lookup_tax_rate, so an agent gets no explicit differentiation from the only other 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?

Usage is only implied: an agent can infer this is the tool for checking quota/entitlement status, and the description supplies the prerequisite of a valid API key. There is no explicit when-to-use versus when-not-to-use statement and no reference to the sibling tool as an alternative.

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 (readOnly, idempotent, non-destructive, closed-world). The description adds value beyond them: the API-key requirement and both accepted header names, plus the plan-gated nature of certain features. It does not mention rate limits or error behavior, so it stops short of 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?

Four sentences, each earning its place: purpose, input modes, return shape, auth. Front-loaded with the core action and 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?

For a 13-parameter tool with no output schema, the description covers purpose, input modes, auth, and return granularity by jurisdiction. It omits error/failure behavior and pagination, which is a minor gap given the schema already documents every parameter.

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 schema descriptions already carry the precision tradeoffs (door-level vs. ZIP-overlap, plan requirements, historical lookback). The description largely restates address-vs-lat/lng and adds little syntax or format detail the schema lacks, 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+resource ('Look up sales and use tax rates') with the geographic scope (US or Canadian location). An agent can immediately tell this apart from the only sibling, get_account_metrics.

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?

Explicitly routes between the two input modes: full street address for door-level accuracy vs. a lat/lng pair for a point lookup, matching the schema's anyOf. It gives clear context but does not state exclusions or when to fall back to the less-precise postalcode option (that guidance lives only in the schema).

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