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

With no annotations, the description carries the behavioral disclosure burden. It discloses persistence across sessions, the need for an API key, and privacy benefits. However, it does not mention overwrite semantics, the return value, or side effects beyond storing, leaving some ambiguity for an agent.

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 front-loaded with the core purpose and remains relatively compact. Each sentence adds useful context: persistence, use cases, and authentication. The motivational sentence about losing information earns its place by guiding the agent on tool selection, though it is slightly long.

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 two-parameter tool, the description covers the core operation and authentication. However, because there is no output schema and no annotation, the absence of details about overwrite behavior and the response format leaves a noticeable gap for an agent invoking the tool.

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%, and both parameters are documented in the schema: key as a namespaced identifier and value as a serialized string. The description does not add parameter-level detail beyond what the schema already provides, so the baseline of 3 is appropriate.

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 a specific verb and resource: 'Store a value under a key so you can read it back in a LATER session.' It also differentiates from siblings by emphasizing cross-session persistence, making it distinct from memory_get, memory_list, and memory_delete.

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 gives clear context for when to use the tool: 'Use this to remember anything worth keeping' with concrete examples like processed items, running lists, and intermediate results. It does not explicitly state when not to use it or name alternatives, but the context is sufficient for an agent to decide.

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