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

Annotations already declare readOnly, idempotent and closed-world behavior, so the baseline is low; the description still adds value by disclosing the return payload ('each with its sources page') and the 2-4 service comparison constraint. It does not say what happens when a supplied service name is not recognized, which is the main remaining behavioral gap.

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?

A single dense sentence with no filler, listing the compared dimensions up front. The telegraphic, verb-less phrasing is slightly harder to parse than a full clause would be, but nothing is wasted.

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 one-parameter, read-only tool with a well-annotated profile, the description covers dimensions compared and output provenance, which is adequate. It leaves open how services are matched and what the comparison output looks like structurally, which matters given there is no output schema.

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 'services' parameter is already documented as names or slugs with minItems 2 and maxItems 4 in the schema. The description's '2 to 4 named services' restates the schema bounds rather than adding meaning such as slug format or matching behavior; baseline 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?

The description names the exact comparison dimensions (cost, insurance, plans, Medicare/Medicaid, prescribing, ages) and the 'side by side' framing makes the compare verb unambiguous, which distinguishes it from the single-service sibling get_online_therapy_service. It never states a verb outright and does not name the alternative tools, so it falls short of a 5.

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 only implied: '2 to 4 named services' signals that the caller must already know service names, hinting that search_online_therapy_services should run first, and 'side by side' implies multi-service comparison rather than single lookup. There is no explicit when-to-use, when-not-to-use, or named alternative.

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