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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses two substantive behavioral traits: only "redirect"-type codes accrue scans, and free-plan owners see a truncated 7-day window while Pro retains full history. That second point directly warns that a result set may be incomplete rather than wrong, which is exactly the kind of caveat annotations cannot convey. It stops short of describing error behavior for invalid or non-redirect IDs.

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?

Four short sentences, front-loaded with the core answer and followed by the two caveats that change interpretation of the results. The opening "Free." fragment is slightly jarring, and the parenthetical price is arguably marketing filler, but nothing is redundant.

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 one-parameter read with no output schema, the description covers the essentials: what is counted, which code types are eligible, and how plan tier truncates history. Remaining gaps (timezone or granularity of "per day", response on an invalid ID) are minor for a tool this simple.

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 `id` parameter is already fully documented in the schema with format, length bounds, provenance (create_qr_code) and an example value, so coverage is 100%. The description adds nothing about the identifier or what happens when it is malformed, which is acceptable at this coverage level but earns no credit.

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?

"How many times a QR code was scanned, in total and per day" gives a concrete verb and resource plus the shape of the result, so an agent knows exactly what it retrieves. It does not need to distinguish itself from the listed siblings (plan, creation, destination update), which cover unrelated resources, but it also never names a boundary against them.

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 context is implied rather than stated: the tool is for reading scan counts, and the note that only "redirect" codes count tells the agent implicitly when results will be empty. There is no explicit when-to-use or when-not-to-use guidance, and the Pro upsell is mentioned without pointing to the sibling tool that would perform an upgrade.

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