List available PCP metrics

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

Annotations only declare readOnlyHint=true; the description adds substantive behavior — large sub-namespaces collapse to a single summary line, only pmlogger-recorded metrics appear, and everything listed is safe to pass to pcp_query_metrics. It also discloses the environment prerequisite, which annotations cannot express.

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 with the core action, then the collapse/drill-down mechanic, then the routing rationale and prerequisite. Every sentence carries distinct information 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?

Covers action, iteration strategy, result contract ('everything listed can be passed to pcp_query_metrics'), alternative tool (pcp_guide) and precondition. With an output schema present and full parameter coverage, nothing an agent needs to call this correctly is missing.

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 coverage is 100% and documents both parameters thoroughly, so the baseline is 3. The description adds real value beyond the schema by explaining the iterative drill-down semantics of 'prefix' (omit to start at top level, re-call with a collapsed name to descend), which the schema only hints at.

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 action (browse/list metrics in the PCP namespace under a prefix) and distinguishes itself from siblings by naming pcp_query_metrics as the consumer and pcp_guide as the curated shortcut. The collapsing behavior of large sub-namespaces is also stated outright, so the agent knows exactly what this returns.

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?

Explicit routing: 'reach for this when you need a subsystem the guide does not cover', plus a hard prerequisite ('Use only if get_system_information() indicates PCP is available'). It also tells the agent how to drill down (call again with the sub-namespace name as prefix), which covers the iterative usage pattern.

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