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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description adds real value by disclosing field exclusions ('Booking notes and session notes are not returned') and the underlying GET endpoint, letting an agent know the response is a partial view.

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?

Dense and front-loaded: returned fields first, then the two special-case caveats, then the endpoint. Every clause earns its place, though the raw HTTP path is somewhat redundant metadata for an agent caller.

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 compensates by listing the returned fields and explicitly noting what is excluded, so an agent knows what it will and won't get. It is close to complete for a two-parameter read tool; only pagination/error behavior is unaddressed, which is minor here.

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 100%, and the record_id parameter is already documented in the schema as group-sessions-only. The description restates that constraint with a bit of added rationale ('one client's view'), so it does not meaningfully exceed the schema and the 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?

States a specific verb+resource ('One session (appointment) by id') and enumerates the returned fields (date, duration, service, practitioner, client, location, status). This clearly separates it from the sibling list_sessions, which returns many sessions rather than one.

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 one conditional usage rule ('For a group session pass record_id to see one client's view'), which is genuinely helpful. However it never states when to prefer this over list_sessions or other lookup tools, so overall guidance is implied rather than explicit.

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