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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuine behavioral context beyond that: the dual response mode (verified status with date when Foundations has published one, otherwise the website's scheduling statement) and the caveat that results are not counselor-specific. It stops short of describing pagination, rate limits, or failure modes, but there is little of that to disclose for a single-filter lookup.

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 tight sentences with zero waste: scope first, response behavior second, the counselor-availability caveat last. Each sentence adds information an agent needs before calling or interpreting results.

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?

There is no output schema, so the description carries the burden of explaining return values, and it does so by describing both possible result shapes. Combined with the annotations covering safety and the fully documented parameter, nothing an agent needs to call and interpret this tool 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?

One optional parameter with 100% schema description coverage and an enum, so the schema already carries the semantics. The description merely echoes the optional office/online narrowing without adding format or selection guidance beyond what the enum provides; the high-coverage baseline of 3 applies.

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+resource+scope: 'Practice-level availability for new clients', with the optional office/online narrowing named up front. It also explicitly rules out the neighboring concept ('Availability is never published for individual counselors'), so an agent can separate it from get_counselor and find_counselors without opening any schema.

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?

Gives clear context for use (practice-level, new clients, optionally one office or online) and an explicit exclusion ('never published for individual counselors'), plus a fallback route (confirm by phone or the booking link). It does not explicitly name a sibling tool to use instead for individual-counselor questions, so it falls just short of full when/when-not/alternative coverage.

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