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

Beyond the annotations (idempotent, non-destructive), it discloses that data is stored as a key-value pair scoped by the agent's identifier, and explains persistence differences: authenticated users get persistent memory, anonymous sessions retain memory for 24 hours. This adds meaningful behavioral context, though it stops short of stating overwrite behavior or any limits.

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, tightly written, with the core action first, then usage trigger, then storage details and companion tools. No extraneous information, and the structure is logical.

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, this description covers purpose, usage, persistence, and related tools. It is complete enough for an agent to know when and how to use it, and the annotations cover safety. Minor details like overwrite semantics are not critical here.

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 schema already provides thorough descriptions for both parameters with examples (key: 'target_ticker', value: 'findings'), and coverage is 100%. The description's extra examples (resolved ticker, target address) are largely redundant with the schema, so it adds only marginal value beyond what is already documented.

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 clear verb and resource: 'Save data the agent will need to reuse later.' It also distinguishes from siblings by explicitly naming recall and forget, and provides concrete examples (resolved ticker, target address, user preference) that clarify the tool's intended use.

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 states exactly when to use the tool ('when you discover something worth carrying forward... so you don't have to look it up again') and references companion tools recall and forget, giving a clear workflow. This is strong guidance for when and how to use it.

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