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

The destructiveHint annotation already signals mutation, and the description reinforces it with 'Permanently delete.' It adds the single-entry scope but does not elaborate on side effects, permissions, or irreversibility beyond what the annotation already implies.

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?

Two concise sentences, with the action and consequence front-loaded. The example and ID source add useful context without wasted words.

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 one-parameter delete tool with a clear annotation, an output schema, and a simple resource, the description fully covers what the tool does and how to obtain the required ID. Nothing essential 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 0%, so the description must compensate. It does so by telling the agent exactly where entry_id values come from: 'Entry ids come from get_custom_metrics.' This is the key semantic needed for the single required parameter.

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 states a specific verb and resource: 'Permanently delete one custom metric entry.' It also clarifies the intended corrective use case with 'e.g. a typo,' and the resource is distinct from sibling tools like delete_workout.

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 provides clear context for when to use the tool: deleting a specific custom metric entry, often to fix mistakes. It does not explicitly name alternatives or when-not-to-use conditions, but for a focused single-purpose tool this is adequate.

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