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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description nonetheless adds real behavioral context: customizing the calculator requires no account while creating the embed requires a free account. That account/prerequisite nuance is exactly the kind of information annotations cannot express.

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?

Two compact sentences with the core purpose front-loaded, followed by supported platforms and the account prerequisite, then the usage trigger. No filler or repetition.

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-only tool with a fully documented schema and no output schema, the description supplies everything needed: what is returned, which platforms the embed targets, the account requirement, and the usage condition. Nothing material to correct invocation 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?

Schema coverage is 100%: the single slug parameter is documented in the schema, including its source ("Calculator slug from search_calculators") and an example. The description adds no further parameter meaning, so the baseline 3 is appropriate.

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 precise verb+resource: returns the embed/style link for a Calcupedia calculator, including what the link enables (styling and getting embed code). This is unmistakably distinct from the sibling tools calculate, run_calculator and search_calculators, all of which do something other than produce an embed link.

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?

"Use it when someone wants a calculator on their website, blog or online store" gives a clear triggering condition. It does not explicitly name the sibling tools as alternatives or state when NOT to use it, so it stops short of the top score, but the routing intent is clear enough for an agent.

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