tmux_has_session

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

Annotations declare readOnlyHint=true, so the description doesn't need to restate that. It adds the return format, which is useful. However, it doesn't disclose any additional behavioral traits like side effects, performance characteristics, or error conditions.

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 extremely concise with a single sentence and a return format spec. No wasted words, but it lacks necessary details about parameters, which makes it too terse for effective use.

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 the tool has two parameters and no output schema, the description should explain inputs and outputs more thoroughly. It does cover the return value minimally, but omits parameter semantics and context for the target field, leaving the description incomplete.

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 0%, but the description provides no explanation of the 'session' or 'target' parameters. The agent cannot determine what values to provide or how they affect behavior. This severely limits correct invocation.

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 purpose: 'Check whether a session exists.' It specifies the return format as a JSON object with a boolean field, making the goal unmistakable. This distinguishes it from sibling tools like tmux_list_sessions or tmux_kill_session.

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?

No guidance on when to use this tool versus alternatives such as tmux_list_sessions or tmux_has_session itself. No exclusion criteria or context for when not to use it. Implicitly it's for a simple existence check, but an agent lacks decision-making support.

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