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

Annotations already cover read-only safety, and the description adds useful behavioral context: it returns the most recent observations first and implies a default of 10 via 'Latest N'. It does not mention update frequency or data format, but these are minor for such a simple 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?

The description is a single concise sentence (18 words) that front-loads the key action and scope. No filler or redundant 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?

For a simple time series tool with strong annotations and no output schema, the description covers the source, series ID, and ordering. However, it does not explicitly state the structure of each observation (e.g., date and value), which is a minor gap given no output schema exists.

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% with the 'last' parameter described as 'Number of most-recent observations (default 10).' The description's 'Latest N observations' mirrors this without adding new semantics, so a baseline 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 description clearly states the tool returns the latest N observations of the Bank of England official Bank Rate, including the specific series ID (IUDBEDR) and ordering ('most recent first'). This is specific and distinguishes it from siblings like 'sonia' or 'get_series'.

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 context is clear: this tool is specifically for the Bank Rate series. It doesn't explicitly state when not to use it or point to alternatives, but given sibling tools like 'get_series' exist, the specificity is implied. No exclusions are needed for a simple data retrieval tool.

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