Change reseller user's package

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

Goes well beyond the annotations (readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=true) by disclosing the 422 failure mode for unknown packages, the 403 refusal for non-reseller accounts, and a configuration prerequisite. The return value ('Returns the updated user') is also stated, which matters because no output schema exists.

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?

Three short sentences, front-loaded with the action, then error behavior, then eligibility constraints. Every sentence carries actionable information and there is no filler.

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 and full annotation coverage, the description fills all remaining gaps an agent needs: what it does, failure codes, eligibility restrictions, environment caveat, and the return value. Nothing material for 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 description coverage is 100% and both parameters carry inline descriptions with examples ('premium', 'johndoe'), so the schema does the heavy lifting. The description adds no parameter-level meaning such as whether the package name must pre-exist or whether assignment replaces or supplements the current package. 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 specific verb and resource: 'Assigns a different package to a user,' which is clearly distinguishable from update_reseller_user, suspend_reseller_user, and the package CRUD tools. It doesn't explicitly contrast itself with the closest sibling (update_reseller_user), so it falls just short of the 5 bar for sibling differentiation.

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?

Provides a clear precondition ('Reseller accounts only') and an explicit exclusion ('regular accounts are refused, typically with 403'), plus an environment-level restriction on MXROUTE_USERNAME form. It stops short of naming what an agent should do instead for regular accounts, so no true alternative routing is given.

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