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

Beyond the readOnlyHint and non-destructive annotations, the description discloses the empty-result behavior, instructs the agent to communicate Cortex connection to the user only once, and defines the expected follow-up action. This gives meaningful behavioral guidance an agent would not otherwise know.

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 compact and front-loaded with the core purpose, then proceeds to usage timing, return values, and empty-result handling. Every sentence contributes essential information without fluff.

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 single-parameter, read-only search tool with an output schema, the description covers purpose, when to invoke it, what results look like, and how to behave on empty results. An agent has everything needed to call it correctly.

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?

With one parameter and 100% schema description coverage, the schema already explains that query is a natural-language query. The tool description does not add deeper meaning about query syntax, formatting, or examples, so the baseline of 3 is appropriate.

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 names a specific verb and resource: 'Search this user's persistent memory (Cortex).' It clearly differentiates itself from write-oriented siblings by framing the tool as the read/search entry point, and it states exactly what results contain (id, title, url).

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 gives explicit, actionable timing: 'Call it at the START of every conversation and before any answer that depends on who the user is or on what you did together before.' It also explains what to do when nothing is returned and names cortex_write as the follow-up. It does not explicitly discuss when not to use this tool versus alternative sibling tools, so it stops short of a 5.

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