exists_key

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

Absent annotations, the description carries the burden of explaining behavior. It clearly indicates a read-only existence check, but does not disclose the return format (e.g., boolean true/false) or behavior on missing keys. The core operation is clear, but some behavioral details are omitted.

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 a single, concise sentence with no unnecessary words. It directly states the tool's action and target.

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 simple nature (one parameter, no output schema), the description is mostly sufficient. However, since there is no output schema, mentioning the return value (e.g., 'returns true if key exists, false otherwise') would enhance completeness, but its absence is not critical for a straightforward existence check.

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 parameter 'key' is fully described in the schema ('Redis key to check') with 100% coverage. The tool description adds no additional meaning beyond what the schema already provides, so a baseline of 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 'Check if a key exists in Redis' uses a specific verb ('Check') and resource ('key exists'), clearly stating the tool's purpose. It is distinct from siblings like get_data or get_key_info, which imply retrieval rather than a boolean existence test.

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?

No guidance is provided on when to use this tool versus alternatives such as get_key_info or get_data. The description simply states what it does without contextual clues for selection.

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