explain_role_selection

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

With no annotations, the description carries the full burden and does well: it discloses that nothing is called remotely, that resolution is deterministic, and it enumerates the precedence chain (explicit override, TOML environment mapping, sole granted role). It does not state what happens when no role resolves or whether authentication is required, so it stops short of full coverage.

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 front-loaded sentences with no filler; the side-effect disclaimer leads and the resolution logic follows. The trailing clause 'without the model ever choosing a role itself' partially restates 'deterministic' and could be folded in, which keeps it just short of a 5.

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?

An output schema exists, so return values need not be described, and the description covers purpose, side effects, and resolution precedence for a moderately complex tool. The remaining gap is parameter-level meaning and the no-role-resolvable case, which matters for an explain tool whose whole value is the explanation.

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 0%, so the description must explain all four parameters. It only loosely ties 'role' to the explicit-override mechanism and 'org' to the TOML environment mapping; account_id vs account_name (why both are required) and the nullability/defaults of org and role are left entirely unexplained.

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 — dry-run deterministic role resolution for one account — and immediately separates itself from siblings by declaring it makes no service call and never lets the model pick a role. That distinguishes it from login, use_org, and list_roles without the agent needing to compare schemas.

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 'dry-run' and 'makes no service call' framing implies this is the inspection step to run before an actual role assumption, but no sibling is named as the alternative and there is no explicit when-not guidance (e.g. 'use use_org to actually assume the role'). Usage is inferable rather than stated.

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