Tool-call metrics

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

Annotations already declare readOnlyHint=true, so the description doesn't need to restate that. It adds valuable context: metrics are in-memory and reset on process restart, and it explicitly states no payloads or secrets are included. This goes beyond the annotations by disclosing the ephemeral nature of the data and the scope of what's reported.

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 description is concise and front-loaded with the core purpose. It lists the metrics in a compact list, adds the metadata-only caveat, notes the reset behavior, and ends with a usage recommendation. Every sentence adds value with no redundancy.

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 parameterless, read-only tool with no output schema, the description is complete. It covers what metrics are reported, the scope (this server process), the ephemeral nature, and the intended use case. An agent has everything needed to decide when to call it and what to expect.

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 has zero parameters, so the schema provides no parameter documentation. The description compensates by explaining what the tool reports and its scope, which is sufficient for a parameterless tool. The baseline for 0 params is 4, and the description meets that by clearly explaining the tool's output.

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 reports in-memory observability metrics for the server process, listing specific metrics (per-tool call count, error count/rate, latency, uptime, circuit-breaker state). It distinguishes itself from siblings by focusing on observability rather than configuration or resource management.

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 explicitly states when to use it: 'Use it to spot a failing tool or a degraded portal upstream.' It also clarifies what it is not for: 'Metadata only — no payloads or secrets.' This provides clear guidance on when to invoke this tool versus alternatives.

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