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

Annotations declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety profile is clear. The description adds behavioral context: scoping to identifier, listing behavior when omitting key, and pairing with other tools. No contradictions.

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?

Three concise sentences, each adding value. First sentence states primary function, second provides usage context, third mentions pairing. 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 retrieval tool with no output schema, the description fully explains behavior (single vs list), scoping, and relationship to sibling tools. Agent has sufficient information to use correctly.

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?

Input schema covers the only parameter 'key' with a clear description. The tool description restates that omitting key lists all keys, but adds minimal extra meaning beyond the schema. Schema coverage is 100%, so baseline 3 applies.

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 tool retrieves a value or lists all keys, with specific verb ('retrieve', 'list') and resource ('value', 'keys'). It distinguishes from sibling tools 'remember' and 'forget' by naming them directly.

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?

Provides explicit when to use: 'look up context the agent stored earlier... without re-deriving it from scratch'. Implicitly advises against using when save/delete are needed, and explicitly mentions pairing with 'remember' and 'forget'. Scoping is also clarified.

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