PAID ($0.005). Historical values of a reference series with effective date ranges, optionally filtered by from/to (YYYY-MM-DD). Pass api_key if you have one; otherwise the response explains how to pay via x402.
| Name | Required | Description | Default |
|---|---|---|---|
| to | No | Latest effective date, YYYY-MM-DD | |
| from | No | Earliest effective date, YYYY-MM-DD | |
| series | Yes | Series id | |
| api_key | No | API key | |
| country | Yes | ISO country code |
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 paid nature ($0.005), the optional api_key behavior, and the fallback payment instruction via x402, which is crucial for a paid tool. It implies a read-only retrieval but does not explicitly state side-effects or error handling, so not 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?
Two sentences, front-loaded with the cost warning, and no wasted words. It efficiently covers purpose, filters, and authentication in a compact way.
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 cost, auth, and filtering, giving a good overall picture. However, with no output schema, it does not specify the exact return format (e.g., list of value-date pairs), which leaves a minor gap. Still, it is sufficiently complete for a straightforward historical lookup 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 coverage is 100%, so the parameters are already well documented. The description adds only minor context, such as the YYYY-MM-DD format and api_key payment semantics, which do not significantly enrich understanding beyond the schema. Baseline 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?
The description clearly states the tool retrieves historical values of a reference series with effective date ranges, which distinguishes it from siblings like get_series and get_snapshot. The scope is specific: it provides time-filtered history, making the purpose unambiguous.
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 usage for historical data needs via 'Historical values' and 'optionally filtered by from/to', offering clear context. It does not explicitly name alternatives, but the sibling names and the phrase 'reference series' help the agent infer when this tool is appropriate.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each of the 11 tools addresses a clearly distinct operation: compliance checking, income tax, payroll, VAT, working days, holidays, series queries (current/history/snapshot/catalog), and settlement date. Even within the tax and calendar families, the descriptions precisely delineate boundaries, so there is no realistic risk of an agent selecting the wrong tool.
The vast majority of tools follow a consistent verb_noun snake_case pattern (check_, compute_, get_, list_, count_). The only deviation is settlement_date, which is a noun phrase rather than verb_noun, but it is still clear and idiomatic. This single outlier prevents a perfect score.
With 11 tools, the server is well-scoped for a reference-data domain covering statutory rates, calculations, calendars, and settlement conventions. Each tool has a distinct purpose and earns its place; the count is neither thin nor bloated.
The server provides strong coverage of its stated domain: statutory tax computations, payroll, minimum wage, VAT, holidays, working days, and settlement dates, plus a generic series API for extensibility. Minor gaps exist, such as payroll only supporting Nigeria and Kenya and no standalone social-security contributor, but the response descriptions explicitly disclose these limits, and the generic series endpoint provides a workaround for common lookups.
