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

With no annotations provided, the description carries the full burden. It mentions 'No parameters' but does not explicitly state that the operation is read-only, non-destructive, or describe the return format beyond listing metrics. Minimal behavioral context is provided, so a score of 2 is appropriate.

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 with only two sentences. The 'COMPUTE.' prefix is unnecessary and adds no value, and 'No parameters' repeats schema information. Otherwise, it is front-loaded with the action ('List') and efficiently communicates the output contents.

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 tool's low complexity (no parameters, no output schema, no annotations), the description provides the essential information about what it lists. However, it lacks explicit context about when to use this tool versus alternatives, and it does not specify the output format. It is adequate but not complete, so a score of 3 is warranted.

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, and the schema confirms this. The description adds redundant confirmation ('No parameters') but does not need to explain anything else. Baseline for 0 params is 4, and the description aligns with the schema without contradiction.

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's purpose with a specific verb ('List') and resource ('every supported metric'), and it distinguishes itself from sibling tools like calc_metric by focusing on enumeration rather than computation. The inclusion of 'with descriptions and required/optional params' further clarifies the output scope.

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?

Usage is implied: this tool is likely used to discover available metrics before calling calc_metric or other computation tools. However, it does not explicitly state when to use it versus alternatives or provide any exclusions, so it only achieves the 'implied usage' level.

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