Invoke action

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

With no annotations provided, the description must carry the full burden of disclosing side effects. It implies a mutation ('Trigger') but doesn't state whether it changes application state, is synchronous, requires specific permissions, or handles errors. The reference to registration is a hint but insufficient for an agent to predict consequences.

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?

A single, front-loaded sentence directly states the core function without any extraneous words. The verb 'Trigger' and resource 'action hook' are placed upfront, making it maximally concise while retaining clarity.

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 1-parameter tool with no output schema, the description is minimal. It lacks information about return values, error behavior, timing (synchronous vs async), and when it is appropriate to invoke. The absence of context about action availability and side effects leaves an agent under-equipped to integrate this tool correctly into a workflow.

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?

The description adds meaning to the single 'name' parameter by explaining it as the name of a registered action hook, which goes beyond the bare string type in the schema. However, it doesn't specify allowed values, format, or how to discover valid names. Given 0% schema coverage and one parameter, the description provides some compensation but not complete clarity.

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 triggers a named action hook, with the verb 'Trigger' and resource 'action hook', and references the registration API via AppMCP.registerAction. It is distinguishable from sibling tools like click or get_ui_tree, but it doesn't explicitly contrast with them, so it falls short of a 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?

The description provides no guidance on when to use this tool versus alternatives like click, type, or wait_for. It doesn't mention prerequisites, conditions, or when an action hook should be preferred over direct UI interactions. This is a clear gap in usability.

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