session_list

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

With no annotations provided, the description carries full burden and does well. It discloses that this is a read-only listing operation (implied by 'List'), specifies the scope ('all sessions regardless of mcp_enabled status'), and explains the relationship with other tools (only mcp_enabled sessions can be targeted). It doesn't mention rate limits or authentication needs, but those might not be relevant here.

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?

Perfectly structured with three distinct paragraphs: (1) what the tool does, (2) when to use it and limitations, (3) how to enable sessions for MCP. Every sentence earns its place with no wasted words. The technical command is appropriately included as it's essential context.

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 this is a simple listing tool with 0 parameters, an output schema exists, and no annotations, the description is complete. It explains purpose, usage context, limitations, and even provides remediation steps for disabled sessions. Nothing essential is missing for this straightforward tool.

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 tool has 0 parameters with 100% schema description coverage, so the baseline would be 3. However, the description adds value by explaining that no filtering parameters are needed - it lists ALL sessions regardless of status, which is useful semantic context beyond the empty 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 clearly states the verb 'List' and the resource 'iTerm2 sessions', specifying exactly what data is returned (IDs, names, titles, sizes, TTYs, mcp_enabled status). It distinguishes from siblings like session_focus or session_close by focusing on listing rather than manipulation.

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?

Explicitly states when to use this tool ('Shows all sessions regardless of mcp_enabled status so you can see which sessions need to be tagged') and provides clear alternatives ('Only mcp_enabled sessions can be targeted by other tools'). It even includes instructions for enabling sessions for MCP access.

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