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

Beyond annotations, the description reveals important behavioral details: scope ('scoped by your identifier'), persistence ('Authenticated users get persistent memory; anonymous sessions retain memory for 24 hours'), and cross-session behavior. These are not available in annotations and materially affect usage. No contradiction with annotations (idempotentHint=true, destructiveHint=false).

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 efficiently structured: first the core action, then when to use, then storage mechanics, then persistence, then related tools. Four sentences, no redundancy, all information earns its place.

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 key-value save tool, the description covers purpose, usage conditions, storage semantics, persistence, and related tools. With no output schema needed and annotations covering safety, this description is complete and self-sufficient.

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?

While schema coverage is 100%, the description adds substantial semantic context by giving concrete examples of what to store ('a resolved ticker, a target address, a user preference, a research subject') and explains the key-value pairing. This goes beyond the schema's generic descriptions and helps the agent choose appropriate keys and values.

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 function: 'Save data the agent will need to reuse later — across this conversation or across sessions.' It uses a specific verb ('save') and resource ('data for reuse'), and distinguishes itself 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?

Explicit when-to-use guidance is provided: 'Use when you discover something worth carrying forward... so you don't have to look it up again.' It also names alternatives and complements: 'Pair with recall to retrieve later, forget to delete.' This clearly differentiates from siblings and gives practical context.

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