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

Annotations already signal idempotent and non-destructive behavior, and the description adds valuable context beyond those: key-value scoping by identifier, persistence for authenticated users, and 24-hour retention for anonymous sessions. It does not contradict annotations and gives the agent useful expectations about memory lifetime.

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 well-structured: it opens with the main action, then gives usage guidance, then explains storage semantics, and ends with companion-tool references. Every sentence earns its place, though it is slightly longer than strictly necessary, so it earns a 4 rather than a 5.

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 tool with no output schema, the description covers purpose, usage, persistence rules, and related tools. The only missing piece is an explicit statement about what the tool returns (e.g., a confirmation), but this is not critical for a storage operation and the description is otherwise complete.

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 already provides full coverage with descriptions for both parameters (key and value), including examples in the key description. The tool description itself does not add new parameter details beyond stating that it is a key-value pair, so it adds no extra meaning beyond what the schema already provides. Baseline 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 saves data for later reuse, using a specific verb ('Save') and resource ('key-value pair'). It also distinguishes itself from the sibling tools by explicitly naming 'recall' and 'forget' as companions, making its role in the memory workflow unambiguous.

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 provides concrete use cases ('a resolved ticker, a target address, a user preference, a research subject') and explicitly mentions the companion tools 'recall' and 'forget'. However, it does not clearly state when NOT to use it, such as for transient data or when a different tool would be more appropriate, so it falls short of a 5.

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