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

Annotations already indicate idempotentHint=true and destructiveHint=false, so the tool is safe to call multiple times and not destructive. The description adds value by explaining the write behavior, key-value storage, scoping by identifier, and session-based persistence. There is no contradiction with 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?

The description is concise, front-loading the main purpose and usage, then providing details on storage semantics and alternatives. Every sentence adds value without redundancy.

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?

Given the simplicity of the tool (2 parameters, no output schema, no nested objects), the description provides all necessary context: what is stored, when to use, how it is scoped, persistence duration, and relationship to siblings. Annotations cover idempotency and non-destructiveness.

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 clear descriptions for both parameters (key and value). The description adds context by explaining that the key should be a mnemonic like 'subject_property' and the value can be any text. Since schema already does the heavy lifting, this is above baseline but not exceptional.

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 purpose: 'Save data the agent will need to reuse later.' It specifies the action (save), the resource (data), and provides concrete examples like 'resolved ticker, target address, user preference.' It also distinguishes from sibling tools by mentioning 'Pair with recall to retrieve later, forget to delete.'

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 explicitly states when to use the tool: 'when you discover something worth carrying forward.' It provides context on scoping ('scoped by your identifier') and persistence differences ('Authenticated users get persistent memory; anonymous sessions retain memory for 24 hours'). It also names alternatives: recall and forget.

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