trmnl_set_fleet_master

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

Annotations already declare readOnly=false, idempotent=true, openWorld=true, destructive=false. The description adds real behavioral context beyond them: the previous master is removed from the fleet, and the endpoint is a PUT to /api/apps/fleet/{installation_id}/master. The demotion side effect is consistent with idempotent=true and non-destructive (the change is reversible by re-promoting), so no contradiction, though it could more explicitly say the demoted device becomes/returns to a mirror.

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 core semantics are front-loaded in two compact sentences and the endpoint line is useful. The trailing 'Changes remote state or starts work. Run only within the user-authorized scope.' is generic boilerplate that adds little value and slightly dilutes the description.

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 fleet mutation with no output schema and two undocumented parameters, key details are missing: the constraints on the device_id (must it be a mirror?), which device becomes master of the old one's role, and any failure modes. The core concept is communicated adequately but not completely.

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 only 33% (only installation_id is documented), so the description carries the burden but adds almost nothing. It never explains that body.device_id is the mirror to promote, nor what the 'profile' parameter does or when a non-default profile is needed.

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?

States a specific verb and resource ('Set the master device') and immediately defines what a fleet master is ('whose playlist and settings the mirrors copy'). The promotion/demotion semantics distinguish it from siblings like trmnl_remove_fleet_master and trmnl_mirror_device, though those siblings are not named explicitly.

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 second sentence implies the precondition that the target must be a mirror in this fleet ('A mirror of this fleet is promoted'), which is useful usage guidance. However, there is no explicit statement of when to choose this over remove_fleet_master, mirror_device, or push_fleet_device, and no prerequisite/error conditions are given.

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