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

Annotations already declare destructive/open-world/non-read-only. Beyond them the description adds genuinely valuable behavior: 'Returns observed state' and the critical 'Five-second timeout is unknown outcome; never retry with a new ID.' It does not specify what state is mutated or permission needs, but the idempotency guidance is unusual and useful.

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 tight sentences, no filler, and the safety-critical timeout/retry warning is placed at the end where it is easy to act on. Telegraphic but each sentence earns its place.

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?

Annotations carry the safety profile and there is no output schema to explain, but a destructive, open-world mutation with 8 required params at 0% schema coverage needs parameter semantics the description does not supply. Timeout handling is covered; the input contract is not.

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 0% for 8 required params; the schema names them with no descriptions. The description touches revision, version, operation ID and 'inspected target' (mapping loosely to expectedRevision, expectedComponentVersion, operationID, targetID), but leaves value, selector, componentID and controlToken completely unexplained, including the 'typed' nature of value.

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: 'Typed component fill through the active sandbox.' An agent can distinguish it from siblings like click/select/set_component_data, though it does not explicitly route against the nearest alternative. Clear enough but not sibling-differentiating.

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?

'Requires revision, version, operation ID and an inspected target for mutations' gives preconditions (must inspect first) but never says when to use fill versus set_component_data or execute_script. Usage is implied through prerequisites rather than explicit alternatives or exclusions.

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