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

Beyond the annotations, the description adds important behavioral context: 'All fields optional' indicates partial update semantics, and 'Owner-only on the backend' discloses an authorization requirement. It does not contradict any annotations, and provides useful constraints not captured in the structured data.

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, compact sentence that front-loads the primary action and includes essential constraints. Every word contributes value, with no redundancy or irrelevant detail.

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 simple update tool with an output schema and annotations covering safety, the description covers the core purpose, usage constraints, and key behaviors. It is complete enough for an agent to select and invoke the tool correctly, though it could add explicit guidance on when not to use it.

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 description groups startAt/endAt under 'reschedule' and title/description under 'edit', adding semantic meaning beyond the schema's bare parameter descriptions. With 67% schema coverage, the description helps clarify the purpose of these parameters, going beyond what the schema alone provides.

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 the tool's function: rescheduling a session or editing its title/description. This distinguishes it from sibling tools like create_session, get_session, and list_sessions by specifying the update action and the specific fields it affects.

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 clear context for when to use the tool (updating an existing session) and notes that all fields are optional, implying partial updates. However, it does not explicitly mention when not to use it or name alternatives like create_session for new sessions.

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