cachly-mcp-server

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

With no annotations provided, the description carries full burden for behavioral disclosure. It states the tool checks existence and returns a count, but doesn't mention important behaviors like whether this is a read-only operation, performance characteristics, error handling, or how it interacts with other cache operations. The description provides basic functionality but lacks operational context.

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 that efficiently convey the core functionality: what the tool does and what it returns. No wasted words, front-loaded with the primary purpose. The description earns its place with essential information in minimal space.

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 2-parameter tool with no annotations and no output schema, the description provides basic purpose and return type but lacks details about the count format (boolean per key? total count?), error conditions, performance implications, or relationship to other cache operations. It's minimally adequate but leaves significant gaps for an agent to use it effectively.

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 50% (only 'keys' has a description). The description doesn't add any parameter-specific information beyond what's in the schema. It mentions 'one or more keys' which aligns with the 'keys' array parameter, but provides no context about 'instance_id' or key format requirements. Baseline 3 is appropriate given the partial schema coverage.

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 ('Check whether one or more keys exist'), the resource ('in the cache'), and the return value ('Returns a count of existing keys'). It distinguishes from siblings like cache_get (retrieves values) and cache_keys (lists all keys) by focusing on existence checking with a count output.

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 implies usage for checking key existence rather than retrieving values, but doesn't explicitly state when to use this tool versus alternatives like cache_get (for values) or cache_mget (for multiple values). No exclusions or prerequisites are mentioned, leaving some ambiguity about optimal use cases.

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