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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds value by explaining the scope (anonymous IP, BYO key hash, or account ID) and the behavior of omitting the key to list all saved keys. It doesn't contradict any annotations and provides context beyond the structured data.

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, front-loaded with the primary action, then use case, then scope and pairing. No wasted words; each 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 retrieval tool with one optional parameter, the description covers functionality, use case, scope, and relationships to sibling tools. Since there is no output schema, it doesn't need to enumerate return types, but it could have briefly mentioned the return format for a missing key. Overall, it's nearly 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 schema already documents the single 'key' parameter with 100% coverage ('Memory key to retrieve (omit to list all keys)'). The description repeats this and adds a few domain examples (target ticker, address, research notes) but does not add significant meaning beyond the schema, so the baseline of 3 applies.

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 a specific verb ('Retrieve') and resource ('a value previously saved via remember'), and explains the alternative behavior of listing keys when the argument is omitted. It distinguishes itself from sibling tools by naming 'remember' and 'forget' as complementary operations, making it obvious this is the memory-read tool.

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 explicit context on when to use the tool: to look up previously stored context without re-deriving it. It also pairs with remember (save) and forget (delete), which are sibling tools. However, it does not explicitly state a 'when not to use' scenario, so it falls slightly short of a full 5.

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