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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description adds value by disclosing the cost ($0.10), API key requirement, and the specific order of evidence sources. It does not contradict annotations.

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?

Two sentences with zero waste. The core purpose is front-loaded, and cost/API key requirement is concise and important. Every clause contributes 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?

With an output schema present and annotations covering the safety profile, the description effectively covers source ordering, usage condition, and cost. It doesn't discuss pagination or errors, but these are minor for a read-only tool with schema-defined returns.

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?

Schema coverage is 100%, so the parameters (query, fact alias, limit) are already well documented. The description adds no additional parameter-specific meaning, but the baseline 3 is appropriate given the schema handles the details.

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 returns evidence/provenance for a claim and explicitly enumerates the source ordering (polaris_learned_facts, life_events/life_event_relationships, memories). This is a specific verb+resource that distinguishes it from siblings like get_memories or get_events.

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 provides a clear condition for use ('when the agent must cite why it believes something') and a critical constraint ('do not invent sources'). It implicitly differentiates from raw retrieval tools by focusing on provenance, though it doesn't name specific alternative tools.

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