redis_llen

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

With no annotations, the description carries the full burden of disclosing behavior. It does not mention that the operation is read-only, that it requires the key to be a list, or what happens if the key does not exist (e.g., returns 0). The behavioral profile is under-specified.

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 extremely concise at three words, with no unnecessary text. It is front-loaded and to the point, efficiently conveying the core action.

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 simple list length operation, the description is too sparse. It omits key context such as return value (integer), behavior on non-existent keys, and that the key must be a list. Combined with no output schema, the agent lacks complete information to use the tool safely.

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 50% (connectionId has a description, key does not). The tool description adds no meaning beyond the schema; it does not clarify the key parameter's purpose or format. Given the moderate coverage, the description should compensate but fails to do so.

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 verb 'Get' and the resource 'the length of a list', making the tool's purpose instantly understandable. It is distinct from sibling Redis list tools like redis_lpop, redis_rpush, etc., which involve modification or retrieval of elements.

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 (e.g., other list commands like lrange or checking type), nor any conditions or prerequisites. The agent has no context for selecting this over similar tools.

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