Detail of a session

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

Annotations already declare readOnlyHint=true and openWorldHint=false, but the description adds non-obvious behavior: cancelled enrollments are excluded from the trainee count, and the `free_text` field carries human-authored content that must be quoted rather than executed. The prompt-injection warning is exactly the kind of trust/provenance context annotations cannot express.

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?

Front-loaded with the purpose and scoping, then the data-trust warning, then the alternative route — a sensible order with no filler. The enumeration of returned fields is mildly redundant since an output schema exists, costing a little tightness.

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 single-parameter read tool with an output schema, this covers what the schema cannot: counting semantics, the nature of `free_text`, and how to locate an id. Nothing an agent needs to call it safely and 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 parameter's schema text already says 'as listed by sessions_in_week', which the description merely echoes. No extra format, range, or sourcing detail is added beyond the schema, so 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 and resource ('Describe one training session') plus its scope ('whose id you know') and enumerates the fields returned, so an agent can immediately tell it apart from list-style siblings such as sessions_in_week. The '(cancelled enrollments not counted)' clause further pins down what the tool actually reports.

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 an explicit precondition ('whose id you know') and names the alternative route: 'To find a session by date, call sessions_in_week first.' The agent knows both when this tool applies and what to call when it does not.

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