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

Annotations already declare destructiveHint=true and idempotentHint=true, so the bar is lower. The description adds useful behavioral details: 'Idempotent and safe to retry... returns deleted=false rather than an error' and 'The value is not recoverable afterwards', enriching understanding beyond the 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?

Five sentences, each earning its place: purpose, usage guidance, scope limitation, idempotency, and irreversibility. The core purpose is front-loaded in the first sentence, making the description both concise and well-structured.

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 destructive nature, idempotency, and TTL interaction, the description covers everything: what it deletes, when to use it, when not to, the single-key limitation, retry behavior, and irreversibility. With annotations and full parameter schema, no significant information 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 description coverage is 100%, with both 'key' and 'namespace' fully documented. The description adds no parameter-specific information beyond the schema, so the baseline 3 is appropriate.

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 opens with 'Permanently remove one key from your namespace', which is a specific verb+resource statement. It clearly distinguishes itself from siblings like kv_set and kv_list by emphasizing 'one key' and 'no prefix or wildcard form'.

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?

Explicitly states when to use: 'Use it when a stored value is wrong or unwanted before its TTL runs out' and when not to: 'if you only want the value to lapse on schedule, do nothing and let the TTL expire instead'. It also names kv_list as the way to find keys, providing a clear alternative.

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