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

Annotations already provide idempotentHint=true and destructiveHint=false. The description adds behavioral context beyond annotations: storage as a key-value pair scoped by identifier, persistence differences for authenticated vs. anonymous sessions (24-hour retention). This clarifies important runtime behavior without contradicting 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?

Each sentence earns its place: purpose, usage scenario, storage model, retention policy, and related tools. It is front-loaded with the primary action and remains concise despite covering multiple dimensions. No fluff or repetition of schema content.

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 2-parameter write tool with no output schema, the description is fully adequate. It explains persistence, scoping, retention, and sibling relationships, covering all relevant context. No critical gaps remain 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 already covers both parameters (key, value) with descriptions and examples (100% coverage). The description adds semantic value by explaining what kind of data is worth storing ('a resolved ticker, a target address, a user preference') and the key-value scoping, helping the agent choose appropriate parameter values beyond simple syntax.

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 opens with a specific verb and resource: 'Save data the agent will need to reuse later.' It clearly distinguishes from siblings by naming recall and forget as complementary actions. The scope (across conversation or sessions) is explicitly stated.

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?

Provides explicit when-to-use guidance: 'Use when you discover something worth carrying forward' with concrete examples. It also names alternatives: 'Pair with recall to retrieve later, forget to delete.' This gives unambiguous direction on when to invoke this tool vs. its siblings.

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