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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, but the description adds substantial behavioral context beyond them: no credit cost, no live Google call, data source (URL Inspection API ~2000/day quota, nightly scan), and that empty results with ok:true mean the scan has not populated the property yet rather than every page being clean. This is exactly the kind of context annotations cannot provide.

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 core purpose and cost/behavior caveats, then details on output shape, pagination, and the empty-result edge case. Every sentence carries unique, useful information with no filler.

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?

With no output schema and only safety annotations, the description supplies the return structure (summary vs rows), pagination defaults, filtering, data latency, and empty-result semantics. An agent has everything needed to call it correctly and interpret the response.

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 50% and the description compensates well: it explains that `rows` is one page (default 200, max 1000), that `summary` is a headline count per coverageState, and that `coverageState` filters to one state matching Google's strings. It leaves `offset` implicit, but the added meaning on limit, rows, and coverageState meaningfully exceeds the schema text.

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: 'index-coverage report for the connected property: which URLs are indexed, excluded, or errored, and why.' It explicitly contrasts itself with the sibling get_search_console_performance, so an agent can route between the two without opening either 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?

Explains key usage conditions: it is FREE (no credits) and makes no Google call, unlike get_search_console_performance, and notes data is populated by a nightly scan so coverage fills in over days. It also explains how to filter to one state. It stops short of an explicit 'use this when X / avoid it when Y' rule, but the alternatives context is clear.

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