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

Annotations already declare idempotentHint=true and readOnlyHint=false. The description adds key behavioral context beyond annotations: 'Stored as a key-value pair scoped by your identifier' and 'Authenticated users get persistent memory; anonymous sessions retain memory for 24 hours.' This explains persistence and auth-dependence, which the agent needs to know.

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 three sentences, front-loaded with the primary action, and every sentence adds value: purpose, usage conditions, and storage behavior with sibling references. 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?

The tool has no output schema, but the description covers the key behavioral aspects: scoping, persistence, and related tools. It does not mention return values or error conditions, but for a simple save operation these are not heavily needed. The description is sufficiently complete for an agent to invoke it 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?

Schema coverage is 100%, with both 'key' and 'value' already described with examples in the input schema. The description only says 'key-value pair' and does not add further parameter-specific details, so it does not exceed the baseline 3.

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's purpose: 'Save data the agent will need to reuse later — across this conversation or across sessions.' It gives concrete examples (resolved ticker, target address, user preference) and explicitly distinguishes from sibling tools by referencing 'recall' and 'forget' for retrieval and deletion, respectively.

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 provides explicit usage guidance: 'Use when you discover something worth carrying forward...' and names alternatives with 'Pair with recall to retrieve later, forget to delete.' This tells the agent exactly when to use this tool and when to use siblings.

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