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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds behavior beyond that: it clarifies the tool returns a snippet rather than writing the file itself, and that the output includes application instructions, plus the phone-oriented intent behind the settings.

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?

One front-loaded sentence that leads with the return value and packs the option summary into a parenthetical. It is dense but readable; the long nested parenthetical is the only minor structural cost.

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?

With no output schema, the description does the necessary work by stating the return is a config snippet plus application instructions, and all five parameters are optional with defaults. It stops short of describing output format or whether defaults are always applied, which is the remaining gap.

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%, so every parameter (mouse, prefix, set_titles, history_limit, set_clipboard) is already documented with defaults and enum values. The description's list of features mirrors the schema rather than adding syntax or trade-off guidance, so baseline 3 applies.

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?

Specific verb ("Return") plus a concrete resource (~/.tmux.conf snippet) with the exact contents enumerated, so an agent knows precisely what it gets. It does not differentiate itself from siblings like tmux_howto or setup_guide, which keeps it below 5.

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?

Usage is only implied: use it when you need a ready-made tmux configuration. There is no explicit when-to-use/when-not, no mention of the sibling how-to or setup tools, and no stated prerequisites, so the agent must infer routing on its own.

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