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

Annotations already indicate a write operation (readOnlyHint=false) and idempotency, but the description adds key behavioral context: storage as a key-value pair scoped by identifier, persistence differences between authenticated (persistent) and anonymous (24-hour) sessions. This goes beyond what annotations provide.

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 three sentences: purpose, usage trigger, and storage/persistence details. It is front-loaded with the most important information and contains no fluff; every sentence adds distinct value.

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 write operation with 2 parameters and no output schema, this description is complete: covers purpose, usage scenario, storage semantics, persistence, and related tools. It fully meets the needs of an agent deciding when and how to invoke it.

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 describes both parameters with 100% coverage, but the description enriches them with domain examples ('resolved ticker', 'target address', 'user preference') and value types ('findings, addresses, preferences, notes'), helping the agent choose meaningful 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 states the tool saves data for later reuse across conversations/sessions, with a specific verb ('Save') and resource ('data the agent will need to reuse later'). It distinguishes from sibling tools by mentioning 'recall' for retrieval and 'forget' for deletion, and provides concrete examples of what to store.

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 frames when to use: 'Use when you discover something worth carrying forward... so you don't have to look it up again.' It also names sibling tools for complementary operations ('Pair with recall to retrieve later, forget to delete'), giving clear context for tool selection.

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