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

With no annotations, the description must carry the full behavioral burden; it does disclose the data source (ECB daily reference rates), refresh cadence (business day), and licensing (free, attribution required). It does not state what happens for an unsupported symbol, whether the call is read-only (implied by 'reference data'), how defaults are applied, or anything about rate limits — meaningful gaps for a zero-annotation tool.

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?

Front-loaded with the core capability and structured as what-it-is then how-to-call. Slightly padded by marketing phrasing ('the same source banks and accounting tools cite', 'clean JSON') that adds little operational 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?

No output schema and no annotations mean the description should fully specify behavior, yet defaults for base/amount, error behavior for invalid symbols, and the shape of the returned rate object are all absent. What it does cover (source, cadence, licensing) is accurate but insufficient for a 3-parameter data 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 description coverage is 0%, so the description must document all three parameters, but it only gestures at 'base' and 'symbols' via the conversion example. The 'amount' parameter is never mentioned, and neither the default base currency nor the default amount (presumably 1) is stated, leaving the agent to guess the semantics of a conversion call.

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 — live foreign-exchange reference rates from the ECB — and the conversion operation ('pass base and symbols, get mid-market reference rates'). This is unambiguous and clearly distinct from any sibling tool (hashing, QR codes, timestamps, etc.).

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 gives a clear usage pattern ('convert between 30+ currencies with a single call: pass base and symbols') and pins the data currency ('updated every business day'). It stops short of explicit when-not-to-use guidance or naming alternatives for real-time tick data versus daily reference rates.

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