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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds useful context beyond that: 'No arguments,' the exact shape of the returned vocabulary, and the worked-example coverage. It stops short of noting caching or size characteristics, so it lands just under full marks.

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?

Front-loaded with the purpose and a single dense paragraph with no filler sentences. The mid-sentence enumeration partially duplicates the output schema, but each item helps an agent decide whether this reference is worth fetching.

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 no-argument reference tool with an output schema present, the description conveys everything needed: what to expect back, when to read it, and how it connects to the mapping-writing flow. Nothing an agent needs before calling is missing.

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?

Zero parameters, which is the baseline-4 case. The description's 'No arguments' is a redundant confirmation of what the empty schema already shows, adding no new semantics.

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 — the rule vocabulary for feed attribute mappings — and enumerates its exact contents (attributes, product fields, operators, value sources, limits, example). An agent can distinguish this reference tool from the sibling mutation tools like update_feed_settings without opening any schema.

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 instructs 'Read this before proposing any mappings.attributes change,' naming the prerequisite condition. It also explains the relationship to update_feed_settings (one call fixes a field for the whole catalog), so the agent knows when this lookup precedes that write.

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