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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds useful behavioral context: a form appears inside the conversation, the resulting plan renders in the same card, and the agent should not ask for missing fields in text. It does not cover failure modes or whether the form can be cancelled.

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?

Three sentences, front-loaded with what the tool does, followed by precise routing rules. Every sentence earns its place: the form fields, the output behavior, the call-order instruction, the pass-through rule, and the sibling alternative.

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?

An output schema exists, so return values need not be explained. Given the annotations, full schema coverage, and sibling tool set, the description supplies everything an agent needs: purpose, call order, exclusion condition, and how to handle already-mentioned parameters.

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 the schema already documents days, year, and country. The description still adds meaningful semantics by saying to pass along anything the user did mention, which clarifies that these are optional pass-through hints rather than required inputs.

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 states a specific verb and resource: it opens a form inside the conversation for planning time off, then shows the plan in the same card. It distinguishes itself from sibling plan_annual_leave by explaining exactly when to use each.

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?

It gives explicit when-to-use guidance: call FIRST when the user wants to plan a holiday and has not already given both a country and a number of leave days. It names the alternative path (plan_annual_leave directly) and instructs not to ask those questions in text.

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