Android Navigation 3 Guide

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

The description adds context that the tool is a 'stable reference' and is safe to call (no destructive actions). Annotations already mark it as read-only, so no contradiction. The description effectively reinforces the non-destructive nature.

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 well-structured with a clear opening, critical warning, and topic breakdown. It is slightly lengthy but every sentence adds value. Could be slightly more concise, but overall effective.

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?

Given no output schema, the description implies return of reference text but does not explicitly describe response format. However, it covers essential usage context, topic options, and guidance, making it largely complete for a reference tool.

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% with a brief parameter description; however, the tool description adds rich detail for each topic value (e.g., 'overview' includes setup, NavKey, etc.; 'migration' includes API mapping). This significantly aids correct parameter selection beyond the schema.

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 it is a 'Complete Navigation 3 reference' and specifies the library version and purpose. It differentiates from sibling tools by emphasizing it is the current official navigation library and explicitly lists covered topics.

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 explicitly instructs 'ALWAYS call this before generating any navigation code' and warns against hallucinating Navigation 2. It provides a clear when-to-use guidance and lists specific topics to request.

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