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

Annotations already indicate a non-read-only operation (readOnlyHint=false) and non-destructive behavior (destructiveHint=false), covering the mutation safety profile. The description adds some parameter behavior (endAt optional) but does not disclose broader side effects like invitations or scheduling conflicts. This meets the baseline for annotation-covered tools without contradiction.

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 two concise sentences, front-loading the core action and then supplying the key parameter constraint. No redundant language or unnecessary details.

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 tool with six parameters (three required), a fully documented schema, and an output schema, the description adequately covers the creation use case. It lacks some behavioral context like invite side effects, but the structured data fills most gaps. Given the tool's complexity, this is sufficient.

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?

The input schema has 100% coverage with descriptions for all six parameters, including ISO-8601 format and allowed invited members. The description's mention of 'Provide an ISO-8601 startAt; endAt is optional' adds no new information beyond the schema. Baseline score of 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 clearly states 'Schedule a campaign session' with a specific verb and resource, distinguishing it from siblings like update_session, list_sessions, and get_session. It also mentions the optional endAt and use cases for planned arcs or recurring play nights, adding further specificity.

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 provides usage context ('useful for laying out planned arcs or recurring play nights') and indicates that startAt is required while endAt is optional. However, it does not explicitly mention alternatives like update_session for modifying sessions, so it lacks explicit exclusions. Overall it gives clear context but no when-not guidance.

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