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

Annotations already declare idempotentHint=true and destructiveHint=false, and the description adds valuable context: storage as key-value pairs scoped by identifier, 24-hour retention for anonymous sessions, and pairing with recall/forget. It does not contradict annotations, and the added behavioral details go beyond the structured metadata.

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 four sentences long, front-loaded with the primary purpose, and every sentence contributes useful information (purpose, usage triggers, persistence, and related tools). It is concise without being under-specified.

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 key-value write tool with no output schema, the description covers all essential aspects: what to store, when to store it, how long it persists, scoping, and how to retrieve/delete. The annotations handle safety, and the description fully supports invocation without requiring additional context.

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 clear descriptions for both 'key' and 'value' parameters, including examples. The tool description does not add significant param-specific details beyond the schema, so a baseline score 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 the tool's verb and resource: 'Save data the agent will need to reuse later.' It distinguishes itself from related tools by explicitly pairing with 'recall to retrieve later, forget to delete,' making its role unique among siblings.

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 guidance on when to use the tool ('Use when you discover something worth carrying forward') with concrete examples (resolved ticker, target address, user preference). It also mentions persistence differences between authenticated and anonymous sessions. However, it does not explicitly state when not to use it, though this is implied by 'worth carrying forward.'

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