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

Annotations already establish read-only, idempotent, non-destructive behavior; the description adds useful beyond-schema context: source data.snb.ch with cube zirepo, Swiss OGD open license, no auth, daily frequency, and the 2021 LIBOR replacement. This is strong additional disclosure, though the phrase 'requested period' is only loosely tied to the limit parameter.

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 the action and series list, then adds historical, use-case, and licensing context in only four sentences. Every sentence conveys useful information for selection or invocation.

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 simple one-parameter read-only retrieval tool with a rich output schema and annotations, the description covers source, license, auth requirements, series contents, and frequency. Nothing essential is missing for an agent to decide to invoke it correctly.

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 100%, and the single limit parameter is already documented with range and default. The description adds no parameter-level detail, so the baseline of 3 is appropriate.

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 first sentence uses a specific verb (retrieve), a specific resource (SARON and compound term rates published by the Swiss National Bank), and enumerates exactly which series are included. This distinguishes it clearly from sibling swissnbm tools covering FX, policy rates, and money aggregates.

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 clear context for when the tool matters, naming Swiss franc derivatives pricing, loan referencing, and interest rate risk analysis. It does not explicitly state when not to use it or name alternatives such as swissnbm.fx.rates or swissnbm.rates.policy, so it falls short of a 5.

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