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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description goes beyond that by disclosing what comes back — a brief method summary, links to the full method, and a sample report — and crucially warns that the sample report uses made-up numbers, preventing an agent from treating those figures as real results.

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?

A single front-loaded sentence with no filler, covering what the method addresses and what the response contains. The phrasing 'the sales Meta ads cause on Amazon' is slightly dense but still readable.

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 zero-parameter, no-output-schema informational tool, the key missing piece would be what the caller receives, and the description states exactly that (method summary, links, sample report) plus the caveat about fictional numbers. Nothing an agent needs in order to call it correctly is absent.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly implies no input is needed.

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 names a specific content resource: an explainer of Spillmark's geo-holdout lift methodology (Meta ads → Amazon sales), plus links to the full method and a sample report. An agent can tell this is a documentation/lookup tool rather than a computation tool. It does not explicitly contrast itself with run_calculator or list_calculators, which keeps it from a 5.

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?

Usage is only implied: an agent infers it should call this when it needs to explain or understand how lift is computed. There is no explicit 'use this when…' statement, no mention of when not to use it, and no pointer to run_calculator for actually computing a lift.

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