Shared preference catalog

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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint, so safety is covered. The description adds that the catalog is engine-owned and that the tool only describes existence rather than returning effective values, which is genuine behavioral context beyond the 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?

Three short clauses front-load the resource and its fields, then immediately disambiguate from oma.pref(). 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?

Zero-param read-only catalog with an output schema present, so return shape is already covered. The description supplies the one thing an agent needs to not confuse this with value retrieval, plus the field list.

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 tool takes zero parameters, so the baseline is 4. No parameter description is needed and none is misleading.

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 resource (engine-owned catalog of SHARED preferences) with the exact fields it returns (key, type, label, default, options). It also contrasts itself with the sibling-ish mechanism oma.pref(), making clear this tool describes rather than reads values.

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?

Explicitly says 'Apps read effective values via oma.pref(); this tool only describes what exists,' which tells the agent this is not the value-fetch path. It doesn't enumerate explicit when-not-to-use cases beyond that, but the routing cue to oma.pref() is clear context.

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