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

Annotations already indicate non-read-only, non-destructive. The description adds useful behavioral context: the session is separate, has its own context, and does not replace the project. This goes beyond the annotations by clarifying the relationship between the session and the existing project.

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?

Three sentences, front-loaded with the main action, followed by a clear use case and a clarifying note. No wasted words; every sentence contributes meaning.

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 create tool with two simple parameters, an output schema, and annotations, the description covers the essential purpose, use case, and side-effect clarification. It is complete enough without needing to explain return values because an output schema exists.

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 schema provides 100% coverage for both parameters (project_id, label). The description adds no additional parameter-level meaning beyond restating that it's 'for a project,' which aligns with project_id. Baseline 3 is appropriate since the schema does the heavy lifting.

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 action ('Create a new development session for a project'), the resource ('development session'), and the scope ('for a project'), while distinguishing it as a 'separate conversation with its own context.' This differentiates it from sibling tools like create_project or list_sessions.

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?

It provides an explicit use case ('Use when the user wants to start a distinct development topic') and clarifies a key non-effect ('does NOT replace or affect the existing project'). However, it does not name alternate tools explicitly, so it falls short of a 5.

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