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

Beyond the annotations (which only say it is a non-idempotent, non-destructive, open-world write), the description discloses real behavioral traits: an outbound email and calendar invite are created, temporary inboxes are refused, and there is a rate limit of 10 bookings per email per 7 days that returns status 'duplicate'. That is exactly the kind of context annotations cannot carry.

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 purpose and side effects are front-loaded, then a scannable parameter block, then the rate-limit caveat. It is slightly long and the parameter list partially mirrors the schema, but every line carries usable information.

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?

For a mutating, open-world tool with no output schema, the description covers purpose, prerequisites, side effects, per-parameter meaning, and even the failure return value ('duplicate'). Nothing an agent needs to invoke 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 description coverage is 0%, so the description carries the full burden and does: it documents all five parameters, marks prospect_email as required with a refusal rule, and supplies concrete format examples for requested_window ('2026-10-06', an ISO interval, 'tomorrow', 'next week'). This adds meaning well beyond the bare titles in the schema.

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 gives a concrete verb and resource ('Book a free 30-minute strategy session with TESSA') and enumerates the observable side effects: finds a slot, creates a Google Meet invite, emails the prospect. This is unmistakably distinct from the read-only siblings like get_pricing or contact_tessa.

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 an explicit gating condition: 'Only call this when the user has asked to book a call and has given their real email address.' That is a clear when-to-use plus a precondition, though it never names an alternative sibling to use instead when the condition fails.

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