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

The description adds substantial context beyond annotations: it explains that rates are derived from interest rate differentials, rounded, and indicative-only. It details all return fields and their meaning, including the interpretation of negative/positive forward points. This fully informs the agent about the tool's behavior and limitations.

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 concise (3 sentences plus a list of returns), front-loaded with the core purpose, and includes an illustrative example. Every sentence adds necessary information without redundancy.

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?

Given no output schema, the description fully covers the return object (forwardRate, forwardPoints, spotMid, settlementDate) and explains how to interpret forward points. It also provides usage context (indicative only) and an example. This is complete for the tool's complexity.

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. The description adds value by providing an example (base=GBP, quote=USD, tenor=3M) and clarifying that tenor can be '1W, 1M, 3M, 6M, 1Y'. It also explains the meaning of return fields which indirectly reinforces parameter purpose.

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 it 'Get an indicative forward FX rate for a currency pair at a specific tenor.' It specifies the verb (Get), resource (forward FX rate), and scope (indicative, specific tenor, currency pair). This distinguishes it from sibling tools like get_spot_rate (spot rates) and resolve_settlement_date (only settlement date).

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 explicitly states that the rates are 'for illustration purposes only — not for execution,' guiding when not to use. It also provides an example (base=GBP, quote=USD, tenor=3M) to illustrate usage. However, it does not explicitly compare to siblings or state when to use this tool instead of get_spot_rate or others.

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