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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond that: the 7/30/90-day deltas are null until a daily snapshot that old exists, and it discloses the 7-day competitor site-gain data. 'Read-only' merely repeats the annotation.

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?

One sentence, front-loaded with the resource and its contents, ending with the read-only marker. The long parenthetical metric list is dense but every item is informative, so little is wasted.

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 carries the return-value burden and does so by naming all metrics plus the null-snapshot caveat. It is largely complete, though the absence of any usage routing is the remaining gap.

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 the single app_id parameter is fully documented in the schema (including the 'omit to use most recent project' fallback). The description adds no parameter-level detail, so the baseline of 3 applies.

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 resource ('the project's Overview metrics') and enumerates the exact metrics returned, so an agent knows precisely what payload to expect. This clearly distinguishes it from sibling readers like get_account, get_program, or get_deliverability.

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?

No guidance on when to prefer this over the many other read siblings (get_account, get_program, get_competitor_suggestions, etc.). The 'Read-only' tag and app_id behavior imply it's a safe lookup, but nothing routes the agent here versus an alternative view.

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