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

The description adds substantial behavioral context beyond the annotations: persistence across sessions, scoping by identifier, and the difference between authenticated (persistent) and anonymous (24-hour retention) sessions. These details are not present in the annotations, making the description highly transparent.

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 appropriately sized and front-loaded, starting with the core purpose and then expanding into usage and technical details. Every sentence adds value—examples, scoping, retention policy, and sibling references—without redundancy or fluff.

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 tool with no output schema, the description is complete: it covers purpose, usage context, persistence behavior, authentication differences, and relationships with sibling tools. There are no significant gaps.

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?

The input schema provides 100% coverage with descriptive examples for both parameters (key and value). The description adds no extra parameter-level details, but the schema already handles semantics adequately, so the baseline score of 3 applies.

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 saves data for later reuse, with a specific verb and resource ('Save data'). It provides concrete examples of what to store (e.g., resolved ticker, user preference) and distinguishes it from siblings by describing the key-value pair storage and pairing with recall/forget.

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?

Explicitly defines when to use the tool ('Use when you discover something worth carrying forward') and mentions the benefit ('so you don't have to look it up again'). It also names sibling tools for related operations ('Pair with recall to retrieve later, forget to delete'), providing clear alternatives.

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