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

Beyond the annotations, the description explains the catalog shape, SKU-keyed entries, field meanings, pricing comparison caveats, base-tier requirements, bundled-free cases, and how to handle selfServe=false items. It also clarifies that unlisted discounts or cheaper-than-direct claims should not be made unless the catalog shows them.

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 description is front-loaded with purpose and the mandatory call-before-quoting rule, then uses bullets to structure return fields and handling instructions. It is longer than a simple catalog tool might need, but the detail earns its place because no output schema exists and the pricing semantics are nuanced.

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 supplies the return structure, field meanings, pricing interpretation, base-tier constraints, free-bundling behavior, and purchasing caveats. Combined with annotations covering read-only safety, this is complete enough for correct invocation and downstream use.

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 no parameter semantics to explain; the schema is empty and fully covered. The description correctly focuses on return data and usage rather than inventing parameter guidance.

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 states a specific verb and resource: fetch the canonical Squish email add-on catalog with current pricing. It also names representative products and distinguishes this from get_email_catalog, so an agent can identify its scope without opening the schema.

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?

It gives a strong imperative usage rule: call this before quoting any add-on price, and do not guess from memory. It references get_email_catalog as related doctrine, but does not explicitly state when to use that sibling instead, so it falls short of full when/when-not guidance.

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