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

Goes well beyond the readOnly/openWorld annotations by disclosing the two-tier data pipeline (TrueFX live ticks for 10 majors, frankfurter.app ECB daily fallback for all other pairs, 30 total), and the failure behavior (available=false + error when no rate exists). This is exactly the operational context an agent needs for a live-data 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 purpose, then source tiering and usage guidance, then return fields. Dense but every sentence carries information; the parenthetical 'genuinely live tick data' is slightly chatty but justified as differentiation.

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 exists, and the description compensates by enumerating the returned fields (converted, rate, source, asOf, available + error). Combined with source-tier and failure disclosure, nothing needed to invoke or interpret the call 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?

Schema coverage is 100%, so baseline is 3, but the description adds value the schema does not: it scopes which currency pairs are served and how each tier is sourced, which matters for choosing from/to codes. It does not add format syntax beyond the schema, so it stops short of 5.

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 (convert an amount between currencies) and immediately distinguishes itself from its non-live sibling workflow.run_forex_currency_converter by naming the live-rate mechanism. An agent can tell which of the two converter tools applies without opening either schema.

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?

Gives a concrete trigger ('what's $X worth in EUR?') and a useful exclusion ('where the rate itself isn't already known'). It does not explicitly route against the non-live sibling, but the live-rate framing provides clear context for selection.

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