HKMA Base Rate

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the agent knows this is a safe read operation. The description adds useful context about the rate's behavior (tracks US federal funds target, moves only when Fed moves), which is beyond the annotations. However, it doesn't disclose details like whether the rate is the current published rate or historical, or any rate limit considerations.

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 two sentences, front-loads the core definition, and adds relevant context without waste. 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?

The tool has a simple parameter set (one optional date), an output schema exists, and annotations cover safety. The description provides enough context about the rate's behavior and significance. It could mention that the date parameter is optional and defaults to the most recent published day, but the schema already covers that.

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%, so the schema already documents the 'date' parameter well. The description doesn't add much about the parameter beyond what the schema provides, but the schema is sufficient. 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 identifies the tool as retrieving the HKMA Base Rate, explains its role as the Discount Window floor and anchor for HKD interest rates, and distinguishes it from siblings by focusing on the Base Rate specifically. The verb 'get' plus the specific resource makes the purpose unambiguous.

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 explains the economic context and when the rate typically changes (only when the Fed moves), which helps an agent understand when to call this tool. It doesn't explicitly name alternatives like get_hibor or get_peg_status, but the context of the Linked Exchange Rate System and the focus on the Base Rate implicitly differentiates it from sibling tools.

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