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

Annotations already declare readOnlyHint=true, indicating safe read-only behavior. The description adds useful context by specifying 'hand-marked free slots', but does not elaborate on other behavioral traits like response format or pagination. It is consistent with annotations.

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 a single sentence that conveys the core purpose without unnecessary words. Every part carries meaning, and it is appropriately front-loaded.

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 complexity (3 required parameters, no output schema, and sibling tools), the description is minimal. It does not explain the return format, behavior when no slots exist, or how this relates to other availability tools. It is adequate but could be more complete.

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 0%, so the description must compensate. It mentions 'for an email within a window', which loosely connects to the email, from, and to parameters, but does not specify data types or format (e.g., timestamps). The description adds some meaning but not full semantics.

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 clearly states the tool reads previously hand-marked free slots for an email within a window. It specifies the verb 'Read', the resource 'previously hand-marked free slots', and the context 'for an email within a window', which distinguishes it from siblings like 'set_manual_availability' (write) and 'get_meeting_availability' (likely computed).

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 implies usage for retrieving manually set free slots, providing clear context that the slots are hand-marked rather than automatically computed. It does not explicitly list exclusions or alternatives, but the sibling list (e.g., 'get_meeting_availability') provides some differentiation.

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