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

Annotations already establish readOnly, idempotent and non-destructive, so the bar is low, yet the description adds real behavioral context: provenance labels for description/services/FAQs (Aisle-generated vs vendor-supplied), conditional price-band presence, category-choice provenance, and rating source. It stops short of covering error/nonexistent-slug behavior, so not a 5.

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 sentences, front-loaded with what is returned before the provenance caveats. Dense but every clause carries information; the second sentence is long due to enumerating conditional fields, which slightly hurts scannability.

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 correctly carries the return-value burden and does so in detail, including which fields are conditional. For a simple one-param read tool this is largely complete, with only error/not-found behavior left unspecified.

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?

There is only one parameter and schema description coverage is 100%, so the baseline is 3. The phrase 'by its slug' reinforces the key but adds no syntax or format detail beyond what the schema already documents.

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 specific verb ('Returns') and resource ('a published wedding vendor') plus the retrieval key ('by its slug'), and enumerates the payload (services, descriptions, FAQs, ratings, photos, links). This clearly separates it from sibling search_vendors and list_vendor_categories, which are list/query tools rather than single-entity lookups.

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 agent can infer you call this to expand a vendor found elsewhere, but there is no explicit when-to-use, no pointer to search_vendors as the way to obtain a slug, and no stated behavior when the slug is unpublished or unknown.

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