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aws_sso_list_assignments

Read-onlyIdempotent

List AWS accounts and IAM Identity Center roles available to an SSO session, including existing profile mappings and per-account errors, before generating profiles.

Instructions

List the AWS accounts and roles an IAM Identity Center login can use, after aws_login_start + aws_login_complete with ssoSession. Read-only. Each role shows profile: the existing config profile that already points at it (generated or hand-written), or null. Per-account failures come back as rolesError while the other accounts still list. If the token is missing or expired the error says to run aws_login_start with ssoSession again. Follow with aws_sso_generate_profiles to write profiles.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "ssoSession": "<ssoSession>"
    },
    "name": "aws_sso_list_assignments"
  }
}

Input Schema

NameRequiredDescriptionDefault
accountIdsNoOnly these 12-digit account IDs. Default: every assigned account.
ssoSessionYessso-session name logged in via aws_login_start.
includeRolesNoDefault true. false returns accounts only (one AWS call).

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv2.7.1

TDQS

A4.7/5.0
Behavior5/5

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

Annotations already cover readOnly/idempotent/openWorld, and the description adds behavior beyond them: per-account failures surface as `rolesError` while other accounts still return (partial-failure semantics), the `profile` field is either an existing config profile or null, and expired-token errors carry a remediation instruction. That is the kind of operational detail 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.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads scope and prerequisite in the first sentence, then adds return-shape, failure-mode, and next-step notes in short declarative clauses. No filler or duplicated annotation restatement; every sentence carries new information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, and the description compensates by explaining the returned `profile` field and the `rolesError` partial-failure channel. Combined with the stated auth precondition, an agent has everything needed to invoke and interpret results for this 3-parameter read tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and the schema already documents accountIds filtering, ssoSession origin, and the includeRoles default/cost tradeoff. The description restates the ssoSession linkage but adds no new syntax, format, or edge-case meaning for the parameters, so baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Specific verb + resource: 'List the AWS accounts and roles an IAM Identity Center login can use'. It states the prerequisite (aws_login_start + aws_login_complete with ssoSession) and names the sibling that writes profiles (aws_sso_generate_profiles), so an agent can distinguish it from aws_list_profiles or the generate step without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit preconditions ('after aws_login_start + aws_login_complete with ssoSession'), an explicit next step ('Follow with aws_sso_generate_profiles to write profiles'), and an explicit recovery path when the token is missing or expired (re-run aws_login_start). The agent knows both when to call it and what to do instead when preconditions fail.

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

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