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

The description adds the TTL aspect, which is beyond the annotations. Annotations already declare destructive and idempotent hints, so the baseline is met. But it does not elaborate on overwrite behavior or error semantics, so it remains average.

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?

One short sentence, front-loaded with the action and object, no wasted words.

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 write operation with fully documented schema and annotations, the description is sufficient. It lacks only discussion of edge cases like overwrites, but given the simplicity and sibling context, it is largely complete.

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 schema covers all parameters with descriptions, and the tool description just restates key-value pair and TTL without additional parameter semantics. Baseline 3 is appropriate due to high 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 uses the specific verb 'Set' with resource 'key-value pair', clearly distinguishing from siblings kv_get and kv_list which are read operations. The optional TTL is mentioned, aligning with the schema.

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 clearly indicates the tool is for setting key-value pairs, which is distinct from the read-only siblings kv_get/kv_list. However, it does not explicitly state when not to use it or name alternatives, so not a full 5.

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