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

No annotations provided, so description carries full burden. It doesn't disclose what data is returned, any limitations, or whether it's a search vs direct lookup. Billing mention is non-behavioral. No contradiction.

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?

Extremely short, but the phrasing is garbled and includes irrelevant billing info. It seems under-specified rather than concise. Not front-loaded with useful content.

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?

A one-param lookup tool with no annotations, no output schema, and no differentiation from siblings. The description fails to clarify what exactly 'Search User' returns and how it differs from get_info_username or get_user_id.

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 has 100% coverage with a simple 'user' param described as 'Nickname' with an example. The description adds no more value. Baseline 3 is appropriate.

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 'Search User to Instagram Billing per call: 1 Credits.' awkwardly conflates the tool's function with billing details. It implies searching a user, but the phrasing is unclear ('to Instagram Billing' is nonsensical). It doesn't clearly state it finds user info, and the sibling tools like get_info_username and get_user_id may serve similar purposes.

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?

No guidance on when to use this tool vs siblings. With many similar get_* tools (get_info, get_info_username, get_user_id), there is zero differentiation. The billing note doesn't help.

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