Set default account

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

Annotations already declare readOnlyHint=false and destructiveHint=false, so safety is covered. The description adds genuine behavioral context beyond that: this mutates a persistent setting whose effect is scoped to single-account tools and only applies when no account is supplied per call. It omits validation behavior for an invalid alias and whether the change is reversible, which keeps it from a 5.

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?

One sentence, zero filler, and the operative concept (which tools are affected, under what condition) is front-loaded. Nothing is repeated from the title or schema.

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 one-parameter state-setting tool with no output schema, the description supplies purpose plus the scope of the change, which is what an agent needs to decide to call it. Minor gaps are error behavior on an unknown alias and confirmation of persistence, neither critical.

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 the single parameter's schema text ("Alias or email of the new default account") already carries the semantics. The description adds no format, resolution, or precedence detail beyond what the schema provides, 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 ("Choose") and resource ("account"), and goes further by explaining the effect: it becomes the account used by single-account tools absent an explicit account. That scope sentence distinguishes it from authenticate and list_accounts. It stops short of explicitly naming a sibling it is not, so a 4 rather than a 5.

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?

"when no account is given" implies the condition under which the setting matters, so the agent can infer this is for establishing a fallback rather than per-call selection. But there is no explicit when-to-use instruction (e.g. call before invoking single-account tools), no exclusion, and no pointer to authenticate for obtaining a valid alias. Usage is implied, not stated.

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