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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the description need not repeat safety. It adds the business-days-only constraint, which is useful. Does not explain behavior for non-business days, but that is a minor gap given annotations cover safety.

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?

Two sentences, no wasted words. States purpose, constraint, and format efficiently. Front-loaded with the core action and object.

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?

Simple tool with one param, full schema coverage, and output schema present. Description covers the essential constraint (business days) and format. Output schema handles return value details, so no additional need.

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% and description reiterates the date format already present in the schema pattern. No additional semantic meaning beyond what the schema provides, so 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?

Description uses specific verb 'Returns' with explicit resource '30-year US Treasury yield' and scope 'for a specific date'. Clearly distinguishes from siblings like get_treasury_yield_current (current) and get_yield_curve (curve).

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?

States 'Business days only' and date format, giving clear usage constraints. Does not explicitly name alternatives or when not to use, but the tool name and context make the specific-date use case obvious. Lacks explicit exclusions but provides adequate context.

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