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

Annotations already establish readOnly, idempotent, openWorld and non-destructive. The description adds genuinely new behavioral context: Google-side rate limiting, avoiding rapid repeats, and the wait-or-switch R2B fallback when blocked. That is meaningful operational guidance beyond the structured hints.

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 tight sentences, front-loaded with the tool's identity and content, then the critical rate-limit guidance. No filler; every clause carries information the agent needs before experimenting.

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?

An output schema exists, so return-value explanation is unnecessary. Given the tool is a documentation/help endpoint, the description adequately signals its scope (tool map, engine semantics, status contract, safe usage) and the key operational caveat.

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 there is nothing for the description to clarify beyond the schema. Baseline 4 applies since no parameter semantics are required.

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 purpose: an 'Agent-facing usage guide' covering tool map, engine semantics, status contract and safe usage patterns. This clearly separates it from the sibling search/fetch tools, though it does not name which sibling it complements. Verb+resource are concrete and unambiguous.

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?

'Read this before experimenting' gives explicit timing for invocation, and the rate-limit sentence routes the agent to an alternative ('switch to an RSS-based tool') when results are blocked. It provides clear context and a fallback path, but does not enumerate when-not-to-use cases.

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