Covered currencies

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

With no annotations, the description carries the burden and does add useful context: the 'coverage in progress while market sources are being added' state and the per-plan coverage flag tell the agent results may be partial and entitlement-gated. It does not state whether authentication is required (the request_free_key sibling implies keys matter) or how large the list is, so gaps remain.

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 dense sentence that front-loads the resource and then the returned attributes. It is tightly packed with no filler, though the run-on list of attributes is slightly harder to scan than a short lead sentence followed by detail.

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 catalog call with an output schema and no annotations, this is nearly complete: it explains what each entry means conceptually, which the schema's field names alone may not. The main remaining gap is confirming whether an API key/plan is needed before calling.

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. The description adds nothing parameter-related and needs nothing.

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 exact resource — every currency of the EMpulse Street FX Index — and enumerates the attributes returned (status, confidence class, source count, coverage since, plan coverage). No sibling tool lists currencies, so differentiation is implicit and unambiguous, though the verb ('list') is only implied by the noun phrase rather than stated.

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 a discovery/catalog call to run before get_street_rate or get_rate_history, but the description never says when to call it or references any sibling as an alternative. No prerequisites or exclusions are given.

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