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

With no annotations provided, the description carries full behavioral burden. It discloses that calendars are national statutory holiday calendars (not CSD/exchange), that the tool provides a per-day trail, and that it refuses rather than guessing. It also mentions pricing ($0.05). These details go beyond basic expectations, though output format specifics are missing.

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 comprehensive and front-loaded with the core purpose. While it is relatively long, every sentence adds valuable information. A minor improvement would be to break it into clearer sections for readability. Overall, it is appropriately detailed for the tool's complexity.

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?

Given the tool's complexity (6 parameters, no output schema), the description explains inputs, behavior, constraints, and exceptions well. It mentions a per-day trail but does not fully specify the output format. The mention of a free companion tool (GET /settlement-conventions) adds context. Slightly more detail on output would raise the score.

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%, so baseline is 3. The description adds substantial meaning beyond the schema: it explains how calendars are used (intersection), the difference between business_days and market+instrument_class, the special calendar 'eu.t2', the enum values for instrument_class, and the citation of primary sources for settlement cycles. This significantly enhances parameter understanding.

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 explicitly states the tool computes a settlement date n business days after a trade date using calendar intersection, with a daily trail. It clearly identifies the resource (settlement date) and action (compute), and distinguishes from sibling tools like count_working_days by focusing on settlement date specifics.

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 provides clear guidance on when to use the tool, such as using 'eu.t2' for euro cash leg and specifying business_days or market+instrument_class. It also explains when the tool refuses (e.g., no cited cycle). However, it does not explicitly contrast with sibling tools like count_working_days or get_public_holidays, which would help an agent decide between them.

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