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

Annotations already signal read/write and idempotence, but the description adds valuable context: key-value scoping by agent identifier, persistence differences for authenticated vs anonymous sessions (persistent vs 24-hour retention), and pairing with recall/forget. This goes beyond the annotations without contradicting them.

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?

Three sentences, front-loaded with the core function, followed by usage guidance and storage behavior. No redundant wording; every sentence earns its place. It efficiently communicates what, when, and how without excess.

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 write operation with no output schema, the description fully covers what the tool does, when to use it, persistence semantics, and relationship to siblings. Nothing critical is missing; the complexity is low and the description is proportionate.

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% for both parameters (key and value), so the schema already provides full technical detail. The description only adds real-world examples of content to store, which is helpful but not parameter-level semantics. This matches the baseline for high schema coverage.

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 this tool from siblings by naming paired tools (recall, forget) and giving concrete use-case examples (ticker, address, preference, research subject). This makes the tool's purpose unmistakable.

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?

It explicitly states when to use the tool ('Use when you discover something worth carrying forward... so you don't have to look it up again') and names the complementary tools for retrieval and deletion. Though it doesn't list negative use cases, the guidance is clear and actionable enough to prevent misuse.

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