What changed this week

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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds behavioral context: the report format (summary first), scheduling capability via HTTP server, and the notion of a periodic check-up. It does not contradict annotations and adds useful operational nuance 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 sentences with zero waste. The first sentence front-loads the purpose and content of the report; the second delivers usage guidance and alternatives. Every clause earns its place, and the structure is clear and scannable.

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 reporting tool with 5 parameters and no output schema, the description conveys the essence of the return value (a report with summary and detailed changes) and mentions scheduling. Combined with the fully described schema and annotations, an agent has enough to call it correctly without missing critical information.

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%, and each parameter (days, endDate, siteUrl, markdown, minClicks) already has a descriptive explanation in the schema. The tool description does not add parameter-specific meaning beyond what the schema provides, so it meets the baseline for high coverage without exceeding it.

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?

The description states a specific verb ('report') and resource ('what moved on a property since the previous period'), enumerating exact contents (totals, gained/lost clicks, queries that stopped/started) and a plain-language summary. It explicitly differentiates from siblings by naming gsc_site_snapshot, gsc_compare_periods, and content_refresh_candidates, so an agent can disambiguate it without opening schemas.

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?

Provides clear when-to-use ('to find out whether anything happened') and when-not-to-use by listing alternatives with specific conditions: gsc_site_snapshot for current state, gsc_compare_periods for custom windows, content_refresh_candidates for slow decay. This explicitly routes the agent to the correct tool based on intent.

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