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

The annotations already state idempotence, non-destructiveness, and non-read-only behavior. The description adds useful behavioral detail beyond those fields: it rejects non-writable scopes with 400 and explicitly avoids silent writes into read-only scopes.

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?

The core behavior is front-loaded and the description is compact. The bilingual suffix and redundant English gloss add minor clutter without harming comprehension.

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 two-parameter, fully documented schema with annotations covering safety and idempotence, the description is nearly complete. It misses only the operational consequence of clearing the target or which scopes are visible to the account, but those are minor gaps.

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 schema already documents both scope_id and profile_id, including 0 as 'no target' and the can_write restriction. The description reinforces those semantics but adds no new parameter-level detail beyond the schema.

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 names a specific verb and resource: setting the default write target for a managed account. It clearly distinguishes this from neighboring scope-rights tools by focusing on a single default write destination and the special value 0 for clearing it.

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?

It gives a clear usage constraint: only scopes where the account has can_write are accepted, otherwise 400. It does not, however, explicitly route the agent to an alternative tool when that condition fails or explain when to clear the target.

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