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

Annotations already declare safe read-only, idempotent, non-destructive hints. The description adds valuable context about scoping ('Scoped to your identifier (anonymous IP, BYO key hash, or account ID)') and the behavior of omitting the key argument (lists all keys). This goes beyond annotations by explaining visibility and listing behavior, which is important for the agent to understand.

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, front-loaded with the core function. Every sentence adds value: the first explains the main action, the second provides use cases, and the third explains scoping and pairing with remember/forget. No wasted words.

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 and no output schema, the description covers all necessary aspects: what it retrieves, how to list, scoping, and relationship to sibling tools. It is complete given the low complexity and rich annotations.

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 100% coverage of the single parameter ('key') with a description and examples, so the baseline is 3. The description adds examples of what keys might contain (ticker, address, notes) but does not add major new semantics beyond the schema. It complements but does not significantly extend the schema's meaning.

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: 'Retrieve a value previously saved via remember, or list all saved keys'. It uses a specific verb and resource, and distinguishes itself from siblings by explicitly referencing 'remember' and 'forget' as complementary tools. It also provides concrete examples of stored context (target ticker, address, research notes), making the purpose unmistakable.

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 says 'Use to look up context the agent stored earlier' and provides scenarios (user's target ticker, address, prior research notes). It also implies when to use versus alternatives by framing it as a memory lookup. It does not explicitly mention alternative tools to avoid using, but the context is clear enough for a memory retrieval tool.

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