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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the 'defaults to the current month' behavior, but does not disclose ordering, pagination, or response details beyond what the output schema likely covers. This is consistent with the mid-level calibration example.

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?

The description is a single, front-loaded sentence that immediately states the action and resource, with no wasted words or repetition. It is appropriately concise for a simple list operation.

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?

Given the simple read-only nature, full schema coverage, rich annotations, and presence of an output schema, the description is complete enough. It states what is listed (campaign sessions), the filtering scope (month), and the default behavior, while the schema handles parameter requirements.

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%, with all parameters (campaignId, year, month) already described including defaults. The description only repeats the month default and adds no new parameter semantics beyond the schema.

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 uses a specific verb ('List') and resource ('campaign sessions') with a clear temporal scope ('for a given month') and default behavior. This distinguishes it from sibling tools like get_session (single session) and create_session/update_session.

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?

The description implies the tool is for listing sessions by month, but it does not explicitly contrast with get_session or mention when to use list_sessions over other session-related tools. There are no exclusions or alternatives stated, so guidance is only implicit.

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