System summary

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is known. The description adds that it provides a compact summary of the real host, which gives context on scope but doesn't disclose additional behavior like response size or latency. No contradiction with annotations.

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?

One sentence, front-loaded with the verb and resource, and lists the included data points efficiently. No wasted words; every element adds value.

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 the presence of an output schema and zero parameters, the description is complete for invocation. It could potentially mention that it reflects the actual host environment, but the phrase 'real host' already covers that. It doesn't discuss any limitations, but for a read-only summary tool this is sufficient.

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?

No parameters exist, so the schema is trivial. The description appropriately makes no parameter claims, satisfying the baseline for zero-parameter tools where there is nothing to clarify beyond what the schema already reflects.

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 it retrieves a compact summary of the host system, listing the included metrics (identity, uptime, disk, memory). It distinguishes itself from more specific siblings by the 'compact summary' framing, though it doesn't explicitly name alternatives like host_identity or disk_usage, leaving some ambiguity about when this aggregated view is preferred.

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?

There is no explicit guidance on when to use this tool versus more specific tools like host_identity or disk_usage. The 'compact summary' phrasing implies it's for a quick overview, but the description doesn't state this preference or exclusions, leaving the agent to infer the appropriate use case.

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