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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true. The description adds meaningful context beyond that: it requires an FXMacroData API key and specifies that an anonymous call returns subscription_required with a subscribe link, plus notes that data preserves issuer, instrument, maturity, curve type, and source precision. It does not cover pagination or rate limits, but it goes well past the annotation baseline.

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 purpose and appropriately sized. It is slightly redundant in repeating the API key requirement in two separate sentences, but otherwise every sentence adds value.

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 9 parameters, 0% schema description coverage, and no usage guidelines, the description is incomplete for correct invocation. It covers purpose and authentication but fails to explain how to use most parameters or when to prefer this tool over related siblings like rate_curve or fx_reference_rates.

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% across 9 parameters, so the description carries the full burden. It mentions issuer, instrument, maturity, curve type, and source precision, which hints at some filterable dimensions, but it leaves currency, start_date, end_date, limit, offset, and measure completely unexplained. Partial compensation only.

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 (Read) and resource (persisted official financial price observations) and enumerates the covered data types (government yield curves, individual securities, overnight benchmarks, reference prices). It is clear but does not differentiate from siblings such as rate_curve, fx_reference_rates, or rate_differentials, so an agent must infer which tool to use.

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 offers no explicit when-to-use guidance or alternatives. It only mentions that an empty result means no stored observations and that an API key is required, which is contextual but not selection guidance.

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