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

Annotations already declare readOnly/idempotent/non-destructive, so those need no restating. The description adds genuinely non-obvious behavior: results are cached from the business calendar (pointing at synced_at) and can go stale, since availability is re-checked live at booking time. That staleness caveat is exactly the kind of context annotations cannot convey.

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?

Two sentences, zero filler, with the core operation front-loaded and the caching caveat trailing appropriately. Every clause carries 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 7-parameter read tool with full schema coverage and no output schema, the description covers purpose, scope, and the key freshness caveat, and it references what the result contains ('names the location used', synced_at). Only the explicit sibling routing 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% and each parameter is already documented in the schema, including the customer_zip nearest-location fallback and date defaults, so the description's brief mention of service/location/dates adds little. Baseline 3 applies when the schema does the heavy lifting.

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?

States a specific verb and resource ('List open appointment slots for a Canopy business') plus scope (one service, one location, date range). It is clearly distinguishable from propose_times or request_booking, though it never names a sibling explicitly to sharpen that contrast.

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 phrase 'the time is re-checked live when you book' implies this is the pre-booking discovery step, but there is no explicit statement of when to use this versus canopy_check_bookable or propose_times. Usage is inferable rather than prescribed.

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