list_sessions

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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering the safety profile. The description adds behavioral context by specifying that only root sessions are returned and that directory filtering applies, which goes beyond the schema. It does not describe return format or pagination, but the presence of an output schema mitigates this. No contradiction with annotations.

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 short sentences, with the first sentence stating the core purpose and the second providing a key scoping constraint. Every word earns its place—no fluff, no redundancy. It is front-loaded with the action and resource first.

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 read-only listing tool with full parameter documentation, annotations, and an output schema, the description is adequate. It clearly defines what the tool does and its scope. The only missing element is explicit guidance on when to choose this over sibling tools, but given the tool's simplicity, the provided context is sufficient for correct invocation.

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%, as all three parameters (sort, limit, directory) have descriptions. The description's mention of 'filtered by directory' aligns with the directory parameter but adds no new semantics beyond the schema. This matches the baseline of 3 for high schema coverage.

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: 'Browse sessions filtered by directory'. It adds a critical scope constraint with 'Root sessions only (sub-agents excluded)', which distinguishes it from sibling tools that might list sub-agent sessions or search sessions differently. The verb 'browse' and resource 'sessions' are specific and immediately convey the action.

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 usage context: browsing sessions at the root level, optionally filtered by directory. The exclusion of sub-agents is a clear when-not-to-use condition. However, it does not explicitly mention alternatives like 'search_history' or 'find_sessions_by_file', nor does it state when to prefer this over them, so it falls short of a full 5.

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