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

Annotations already establish read-only, non-destructive, closed-world behavior, so the bar is lower. The description still contributes real behavioral context beyond them: the data is fabricated about a specific fictional coffee roaster and no authentication is required, which tells an agent it can call this freely without credentials or account state.

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?

The purpose and data-shape are front-loaded in the first sentence, which is strong. However, the trailing 'Made-up data, no login. No login needed.' repeats the same no-auth fact twice in two consecutive fragments, wasting the closing position that could have carried usage guidance.

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 usefully enumerates what the response contains (visibility numbers, rivals, ranked plan), which is the main thing an agent needs. For a one-optional-parameter read tool the definition is essentially complete; only explicit alternative routing is missing.

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 single optional 'fields' parameter is fully documented in the schema, including the comma-separated syntax and the token-saving rationale. The description adds nothing about this parameter, so the schema carries all the meaning — a baseline 3 under 100% schema coverage.

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 gives a concrete verb and resource (shows a finished sample report) plus the actual content of that report — visibility numbers, rivals, ranked plan — and frames it as fictional demo data. That is enough to distinguish it from get_report or list_reports, which imply real account data, though no sibling is named explicitly.

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: the 'made-up data, no login' framing suggests this is for previewing a report's shape before creating a real one, or for testing without credentials. There is no explicit when-to-use statement and no routing to the real alternatives (get_report, start_report, create_report) that an agent must choose between.

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