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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false, idempotentHint=false), so the bar is lower. The description usefully adds the required write scope, but says nothing about what happens on a duplicate assignment (relevant given idempotentHint=false) or the resulting record.

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 short sentences, purpose front-loaded, and the scope requirement placed second. Nothing wasted; every clause carries information an agent needs.

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 two-parameter mutation with no output schema, the description covers the essentials but omits duplicate-handling behavior, whether the vendor/site must pre-exist, and any response information. Annotations carry the safety profile, so this is adequate but not complete.

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 description coverage is 100% with only two UUID parameters, both documented as required in the schema itself. The description adds no format, constraint, or referential meaning beyond what the schema states, so the baseline 3 applies.

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 and resource ('Assign a vendor to a site'), which lets an agent distinguish it from sibling creation tools like create_vendor or create_site. It does not explicitly contrast with the related delete_vendor_site_assignment or list_vendor_site_assignments, but the purpose is unambiguous.

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?

The only guidance is a permission requirement ('Requires vendor_site_assignments:write scope'). There is no statement of when to use this versus delete_vendor_site_assignment or bulk_create, nor any prerequisite like the vendor and site already existing.

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