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

Annotations already declare readOnly/idempotent/destructive=false, and the description adds real behavioral context beyond them: it never raises protocol errors, returns a structured {"error": ...} with remediation, and is safe to retry after correction. It also discloses the no-shared-window verdict shape.

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?

Purpose is front-loaded and each sentence carries information (input example, return shape, exclusion, error contract). Slightly dense with multiple JSON snippets, but no filler.

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, yet the description still gives enough of the return shapes and the error contract that an agent can interpret results and recover from bad input. Nothing needed to invoke or handle it correctly is missing.

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, and the description goes further with a concrete example ({"offsets_utc": [-8, 1, 5.5]}) that demonstrates one offset per participant and fractional offsets. Defaults for work_start/work_end are left to the schema, so it doesn't fully exhaust parameter guidance.

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 first sentence names a specific verb and resource ('find the shared meeting window') and scopes it ('across time zones inside working hours'). It is explicitly distinguishable from siblings like recurrence_expand and single-time conversion.

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 states when to use ('people in different zones need one shared slot') and when not ('not for converting a single known time... not for expanding a recurring series (recurrence_expand)'), naming the alternative sibling directly.

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