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

Annotations already convey read-only, open-world, idempotent, and non-destructive behavior. The description adds meaningful context beyond that: the exact data series code, data source (BoE Interactive Database), licensing note, and the fact that no authentication is required. No contradictory claims are present.

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?

Three sentences, no filler. The core definition is front-loaded, followed by the return-window behavior, then provenance/licensing. Every sentence earns its place.

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 tool with one optional parameter, an output schema, and safety-revealing annotations, the description is complete. It covers what is returned, the data window, source attribution, and access requirements — nothing an agent needs to invoke it correctly 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 description coverage is 100% — the sole parameter last_n is fully documented with min, max, default, and series frequency. The tool description merely restates the default and max values without adding new semantic meaning, so the baseline of 3 applies.

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 states a specific verb and resource: 'Daily history of the Bank of England Official Bank Rate... Returns the most recent N days.' It names the series ID (IUDBEDR) and the policy context (set by the Monetary Policy Committee), which distinguishes it from the sibling bank-of-england tools (e.g., mortgage_2y_fixed, sonia) without requiring schema inspection.

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 intended use is implied clearly: this returns the BoE base rate history with a configurable lookback window. However, it never mentions alternatives or gives explicit when-to-use versus when-not-to-use guidance, even though related sibling tools exist in the same namespace.

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