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

Beyond the annotations (readOnly/idempotent/non-destructive), the description discloses the analysis methodology (7 days before vs up to 7 days after on cost, clicks, conversions), the verdict logic (win/loss/flat/too new to judge), and platform-specific handling (non-Google/Meta changes listed without a verdict). This is the qualitative behavior an agent needs and cannot infer from structured fields.

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?

Three front-loaded sentences: purpose, methodology, and usage. Every sentence contributes unique information (scope, comparison window, when-to-use) with no filler, despite being information-dense.

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, the description compensates by explaining what the return contains: per-change before/after comparisons and win/loss/flat/too-new verdicts, plus the platform caveat. For a read-only analytical tool, this is complete enough to call correctly.

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 the days and client parameters are already documented by the schema. The description's 'last N days' phrasing loosely echoes the days parameter but adds no format or semantics beyond it. Baseline 3 is appropriate when the schema carries parameter meaning.

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 (review) and resource (changes confirmed through Agency MCP) and adds precise scope: the 7-day pre/post window, the metrics compared, and the verdict categories. No sibling in the list does anything similar, so an agent can confidently select it.

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?

It gives explicit context ('Use for a weekly review or when asked whether recent changes worked'), which tells the agent when to invoke it. It doesn't name a competing alternative, but no sibling tool overlaps in function, so there is little to exclude.

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