Android Architecture Reference

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds meaningful behavioral context the annotations do not: that the content is an official curated guide, that it should be fetched proactively before structural decisions, and that a 'list' sentinel enumerates topics. It omits that content is session-cached and re-sent only via the refresh flag, which lives only in the schema.

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 short sentences, front-loaded with the purpose, then the usage imperative, then the discovery sentinel. The parenthetical topic enumeration is long but arguably earns its place by defining the accepted vocabulary.

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 read-only reference lookup with no output schema, the agent knows what to pass and roughly what it gets back (a topic guide). It would be stronger with a sentence on return shape (e.g. markdown guide text vs. code samples) or how to chain results into further design work.

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 description coverage is 100% – both 'topic' and 'refresh' carry their own descriptions including the 'list' sentinel and session-cache semantics. The description largely restates the schema's topic examples, adding no syntax or format information beyond it, so the baseline 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?

States a specific verb and resource: it retrieves an official Android architecture guide for a named topic, and it enumerates the valid topic space. It does not, however, distinguish itself from overlapping siblings such as android_navigation3_guide, android_testing_guide, or kotlin_best_practices, whose topical coverage intersects with the listed 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?

"Call before proposing app structure" gives a clear triggering context for the agent, and "Pass 'list' for all topics" gives a concrete discovery path. There is no when-not guidance and no routing advice for the overlapping sibling guides, 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.