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

The description complements annotations (readOnlyHint, idempotentHint, destructiveHint) by disclosing scoping (anonymous IP, BYO key hash, account ID) and the pairing behavior. No contradictions; it adds meaningful context beyond annotations.

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?

Four concise sentences, each serving a purpose: core function, usage context, scoping, and sibling pairing. No unnecessary words, and the structure is logical and easy to parse.

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 single-parameter tool with full annotations, the description covers purpose, usage, scoping, and sibling relationships. It does not specify the return format (e.g., what a retrieved value looks like), but given the simplicity and lack of output schema, this is a minor gap.

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 provides 100% coverage with a 'key' parameter description. The description restates that omitting key lists all keys, which matches the schema. It adds no new semantic meaning beyond what the schema already conveys.

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 by key or lists all keys when omitted. It explicitly names the companion tools (remember, forget) for differentiation, leaving no ambiguity about what it does.

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 explains when to use: 'look up context the agent stored earlier... without re-deriving it from scratch.' It also mentions scoping and pairs with remember/forget, effectively guiding use versus alternatives.

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