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

Annotations already supply read-only/idempotent/destructive hints, and the description adds useful storage traits: encryption and cross-session persistence. It does not contradict the annotations, and it does not need to restate the safety hints.

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 short sentences convey the operation, resource, security property, and persistence behavior with no filler or repetition of the title. Key facts are front-loaded.

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?

With full schema coverage, an output schema, and the given annotations, the description covers the essential invocation context for a simple store operation. A minor gap is that it does not point to memory.recall or clarify overwrite/TTL edge cases, but those are not required for basic correctness.

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 coverage is 100%, so key, value, and ttl are already documented. The description only echoes the key-value relationship and encryption already present in the schema, adding no new parameter-level meaning.

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 names a specific verb ('Store'), a concrete resource ('key-value pair in the agent's encrypted, persistent memory'), and a key behavioral property ('Survives across sessions'). This is sufficient to distinguish it from the sibling memory.recall, which is the retrieval counterpart.

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 persistence framing implies the tool is for values that should outlive the current session, so an agent gets a general sense of when to call it. However, it does not explicitly say when not to use it or mention memory.recall as the alternative for reading stored values.

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