aws_assume_role

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

Annotations indicate readOnlyHint=false and openWorldHint=true. The description adds significant behavior: writes to ~/.aws/credentials, does not return raw keys, returns profile name and expiration, and explains timeout default and adjustment. Could mention potential profile overwriting, but overall good.

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?

A single dense paragraph with all key information front-loaded. Every sentence adds value without redundancy. No wasted words.

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?

Given 8 parameters, no output schema, and side effects (file writing), the description covers the main behavior, parameter details, and security aspects (keys not returned). Slightly lacking mention of profile overwrite risk, but otherwise complete for practical 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?

Schema coverage is 100%. The description adds valuable context for each parameter: roleArn with example, sessionName with pattern and CloudTrail, durationSeconds with range and default, externalId condition, sourceProfile and targetProfile defaults and auto-prefix, region defaults, and timeoutMs with cold-start rationale.

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 clearly states the tool's action: call STS AssumeRole and stash credentials as a named profile. It uses specific verbs and resources, and distinguishes from siblings like aws_call (which executes commands) and aws_whoami (which displays identity) by focusing on role assumption and credential caching.

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 description provides a clear use case: cross-account access using a source profile to assume a role in another account. It explains how subsequent tools can use the stashed profile. However, it does not explicitly state when not to use this tool or contrast with alternatives like aws_session_set.

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