devices_add

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

Adds genuinely non-schema context: the effect starts at default settings, the call returns the chain, and the operation is undoable. "Undoable" in particular is not derivable from the annotations, which only say destructiveHint=false and idempotentHint=false. It does not explain failure modes (invalid device name, full chain), so not a 5.

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?

Three short sentences with zero filler, front-loaded with the action, then the follow-up tool, then the return/undo facts. Every clause carries information an agent would otherwise have to infer.

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 a 100%-covered schema and no output schema, the description covers what the tool does, how to configure afterwards, what it returns, and reversibility. Missing only edge-case behavior such as an out-of-range position or an unknown device name.

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%, so the baseline is 3; the description still adds value by stating that omitting position appends to the end of the chain, a semantic the schema does not spell out. It also anchors the device parameter to the devices.types vocabulary.

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 ("Insert a builtin effect ... into a chain") plus the target scope (end of chain or an explicit position). This cleanly distinguishes it from siblings such as devices_remove, devices_set_params, and devices_list without requiring schema inspection.

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?

Routes the agent to devices.types for valid effect names and to devices.set_params for configuring the newly inserted effect, which is concrete alternative-routing guidance. It stops short of explicit exclusions or prerequisites (e.g. track must exist, chain length limits), so it is clear but not exhaustive.

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