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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so 'Does not change anything' is largely redundant. The description does add genuine behavioral context the annotations cannot: that results include period-over-period comparison and KPI-target progress, which shapes how the agent should interpret the output. No auth, rate-limit, or pagination detail is given.

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, no filler, with the core reporting scope front-loaded ahead of the safety note and the related-tool list. Every clause carries information.

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 values need not be described, and annotations carry the safety profile; the description covers scope, breakdowns, comparison behavior, and routing hints. The only real omission is explicit when-to-use guidance against the named siblings, which is minor given the rest of the coverage.

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%, so to/from/marketId/pillarId are already documented, and the description adds no syntax or format guidance for them. It does mention the reporting dimensions (channel, post, pillar, angle), which loosely corresponds to pillarId filtering and to what the output slices by, but this is marginal over what the schema provides.

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 ('Reports how published content performed over a period') and enumerates the exact breakdowns returned: reach, engagement, clicks by channel, post, pillar and angle, plus period-over-period change and KPI progress. This clearly separates it from get_search_performance and search_posts.

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?

The description disambiguates with 'Does not change anything' and lists 'Related: get_search_performance, get_calendar, search_posts', which implies the neighborhood of alternatives. However, it never states the condition under which an agent should pick this tool over those related ones — no 'use this when you want X, use get_search_performance for Y'.

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