List Hosts

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

Annotations already establish readOnlyHint=true, so the safety profile is covered. The description adds genuine operational context beyond that: default page size of 20, how to page forward with offset, and a summary mode to shrink response size. However, the summary parameter appears only in examples and not in the schema, so the behavioral promise is not fully backed by a structured field.

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 purpose and usage triggers are front-loaded before the examples, so an agent gets the essentials immediately. The example block is somewhat padded — two of the five examples both demonstrate pagination and one relies on an undocumented parameter — but no sentence is purely 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?

For a read-only list tool with all 7 optional parameters fully documented, the description covers selection, filtering, pagination, and response-size control. With no output schema, it could say more about what a host record contains, but that gap is minor for an enumeration endpoint.

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 description coverage is 100%, so every one of the 7 parameters is already documented, and the baseline is 3. The examples do show realistic combinations of service, role, status, limit, and offset, which adds modest value, but they also demonstrate list_hosts(summary=true) for a parameter absent from the input schema, potentially misleading an agent into an invalid call.

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 names a specific verb and resource ("Retrieve hosts from Mackerel") and enumerates concrete capabilities: listing, filtering by service/role/name, and status checks. It doesn't explicitly distinguish itself from siblings like list_services or get_host_metrics, but the resource boundary is obvious from the name and text.

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 "USE THIS TOOL WHEN USERS" block plus five worked examples make the intended invocation contexts very clear, including filter combinations and pagination. It stops short of naming an alternative tool (e.g., pointing to get_host_metrics when the user wants metrics rather than host records), which keeps it below a 5.

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