Set default host/session/window/pane

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

With no annotations, the description carries the burden of behavior disclosure. It reveals a key behavioral trait — 'Omit fields you do not want to change' — indicating partial updates and persistence. However, it doesn't state return values, scope of persistence, or whether defaults are global or per-context, which weakens transparency.

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?

Two short sentences, front-loaded with the core action. Every word earns its place; no filler or redundancy.

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 tool with four optional parameters, no output schema, and no nesting, the description covers the essential usage and behavior. The only gap is ambiguity about the exact scope of 'defaults' and how they apply, but this is minor given the tool's simplicity.

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 coverage is 100%, giving the baseline of 3. The description adds collective parameter meaning beyond individual field descriptions: 'Omit fields you do not want to change' tells the agent that each omitted parameter remains untouched, which is a useful semantic that the schema alone does not convey.

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 with the verb 'Persist' and the resource 'defaults'. It's distinct from sibling tools like tmux_get_default, though it doesn't explicitly name the four target fields (host/session/window/pane), which are only in the title and schema.

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 phrase 'for later tool calls' implies when this should be used, but the description does not explicitly contrast it with tmux_get_default or mention any exclusions. No alternatives are named, so guidance is implied rather than direct.

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