get_api_coverage

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds the return shape (tools/resources/not_yet_supported), which is useful context, but since an output schema exists this partly duplicates structured data and adds nothing about limits or resource URI semantics.

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?

Front-loaded purpose statement followed by a compact usage note and an indented section breakdown. Every sentence earns its place with no filler.

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?

Given an output schema already exists, the description goes slightly beyond what is required by naming all three sections. It remains silent on the horizon:// resource addressing scheme and any size or pagination expectations, so it is complete but not exhaustive.

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 tool takes zero parameters, so the baseline is 4; there are no inputs whose meaning could be explained further.

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: list all available Horizon MCP tools, resources, and unsupported operations. This is a meta/discovery tool clearly distinguishable from the operational siblings (get_settings, list_machines, etc.), and the three-section breakdown makes its scope unambiguous.

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?

Explicitly says when to call it: before attempting a task, or when informing users which features are supported. That is strong positive guidance, but no when-not condition or alternative discovery path is named (there is effectively no sibling alternative, so the gap is minor).

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