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

The annotations already declare readOnlyHint and idempotentHint, but the description adds critical behavioral detail: 'Errors: on invalid, missing, or malformed input this tool never raises a protocol error — it returns {"error": "<what is wrong and how to fix it>"}. Every call is read-only and idempotent, so after correcting the input it is always safe to retry.' This goes beyond the annotations by detailing error handling and retry safety, which is valuable context for an agent.

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 well-structured: a clear opening purpose, a practical example, usage guidance, error handling, and retry advice. Each sentence adds value—no verbosity or repetition. It is front-loaded with the most critical information (purpose) and then progressively adds detail, making it easy to scan.

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 has 6 parameters (including optional ones), an output schema (not shown but indicated), and annotations covering safety, the description is remarkably complete. It covers the decision context, an example output, error behavior, and where it fits relative to siblings. There are no significant gaps; even the premium licensing note is a minor extra. This is comprehensive for a tool of this complexity.

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 baseline is 3. The description adds a concrete example (typical input and output) that clarifies how the parameters interact (e.g., unit_cost, moq, cash_available, lead_time_days produce moq_cost, months_of_cover, etc.). This example enriches parameter understanding beyond the schema's individual descriptions, making the tool's usage more intuitive. However, it does not detail individual parameter nuances, so a 4 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 opens with a clear statement of purpose: 'Decide how much to order against demand, lead time and the cash you have.' It specifies the resource (how much to order) and the criteria. It also distinguishes itself from a sibling tool explicitly: 'Not for the margin each unit earns — that is margin_check.' This is specific and 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 provides explicit usage context: 'Use before committing to a supplier's minimum.' It also states an alternative tool for a different purpose ('margin_check'). This directly addresses when to use this tool and when not to, with a named alternative, exceeding the minimum requirement.

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