cachly-mcp-server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behavioral traits: the lock auto-expires after ttl_ms to prevent deadlocks, returns a fencing token on success, and mentions the retry mechanism. It doesn't cover error conditions or what happens on failure, but provides substantial operational context for a distributed locking tool.

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 perfectly sized with three focused sentences that each earn their place: states the purpose and mechanism, describes the return value and safety feature, and provides usage guidance. No wasted words, well-structured, and front-loaded with the core functionality.

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 distributed locking tool with 5 parameters, no annotations, and no output schema, the description provides good contextual coverage. It explains the Redis implementation, safety mechanisms, return value, and relationship to the release tool. The main gap is lack of information about error conditions or what the fencing token actually represents, but overall it's quite complete for its complexity level.

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%, so the schema already documents all 5 parameters thoroughly. The description adds minimal value beyond the schema - it mentions ttl_ms as a safety mechanism but doesn't provide additional semantic context about parameters like instance_id or key. Baseline 3 is appropriate when the schema does the heavy lifting.

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 specific action ('Acquire a distributed lock'), technology used ('using Redis SET NX PX (Redlock-lite)'), and distinguishes from its sibling tool cache_lock_release. It explicitly identifies what resource is being acted upon (a distributed lock) and the mechanism involved.

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 about when to use this tool (to acquire a lock) and explicitly mentions the alternative tool for freeing the lock early ('Use cache_lock_release to free the lock early'). However, it doesn't specify when NOT to use this tool or compare it to other locking mechanisms that might be available.

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