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

Annotations already establish readOnly, idempotent, non-destructive, and closed-world behavior, so the bar is lower. The description adds genuinely new context: the result is grouped into who/what/how, discontinued offerings (group therapy, seminars) are absent, and returned ids are reusable elsewhere.

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 tightly written sentences, front-loaded with the core action and scope. No filler, and each clause (grouping taxonomy, id reuse, exclusions) carries distinct 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?

With no output schema, the description carries the return-value burden and does so: it explains the grouping, the presence of a usable id per service, and the exclusion of discontinued items. For a simple single-parameter list tool, nothing needed to call 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% and the single enum parameter is fully documented, so the baseline is 3. The description does gloss the taxonomy ('who we help, what we help with, how we work') which clarifies three of the enum values, but it never explains the 'other' category the schema exposes.

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 (lists all talk-therapy services) and immediately bounds scope: grouped by website taxonomy and excluding discontinued offerings. It also distinguishes itself from siblings by naming find_counselors and get_service as consumers of the ids it returns.

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?

Usage is implied rather than stated: the mention that ids are 'usable with find_counselors and get_service' signals this is the discovery/entry-point tool, but there is no explicit 'use this when…' or 'use get_service instead if…' guidance against the sibling get_service.

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