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

The annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is fully covered elsewhere. The description adds one genuinely useful behavioral fact — the returned id is the value to pass as account_id downstream — but says nothing about what fields come back per account (handle, username, avatar) or what an empty result means.

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 sentences, no filler, and the core identity plus the account_id hand-off are stated before the applicability condition. Nothing in it repeats the title verbatim without adding information.

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?

There is no output schema, so the description carries the burden of explaining the return value; it discloses the id field but not the other likely fields the agent needs to match a username or description to an account. For a zero-parameter, low-risk list tool this is nearly sufficient, with that one gap.

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?

The tool takes zero parameters, so the schema is complete and the description correctly adds no input coaching. Its mention of account_id describes output usage rather than input, which is a reasonable, non-redundant addition.

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 (lists connected Threads accounts for this member) and clarifies its unique role: it is the source of the id that every other tool consumes as account_id. That separates it cleanly from settings-oriented siblings like list_account_settings or get_account_settings.

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 an explicit trigger condition — whenever an account id is needed and the user referred to an account by username or description — which is actionable guidance, not just a description. It does not name any when-not cases or an alternative tool, so it stops short of the top of the scale.

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