Get Similar Accounts

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

Beyond the read-only annotation, it discloses what matters operationally: no pagination, frequent empty results, billing even when empty, one request per call, ~1 unit cost, API-key requirement, and a cost estimate per result. That is exactly the kind of context annotations do not carry.

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?

Four compact sentences, front-loaded with the core action and followed by scoping and cost facts; nothing is padded. 'Read-only' slightly restates the readOnlyHint annotation, a minor redundancy but not enough to undermine the tight structure.

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, single-page read tool with an output schema, the description covers the operational facts an agent would otherwise get wrong: result volume, empty results, and billing. It needn't explain return values, but it could say more about what the result list looks like or how userId failure is signaled.

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%, so both userId (numeric pattern and follow-up call for usernames) and responseFormat are already fully documented in the schema. The description adds no parameter-level meaning beyond that baseline, which fits the 3 baseline.

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 uses a specific verb and resource: it fetches the accounts X lists as similar to a user, a resource no sibling tool covers. An agent can distinguish it from user_followers_list, user_affiliates, or user_lists without opening the schema, even though no sibling is named explicitly.

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 supplies concrete context an agent needs before calling: a single page with no cursor, results are often empty, and an empty result is still billed. It stops short of naming alternatives or when not to use this tool, so it lacks the explicit routing that a 5 would require.

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