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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint:false and openWorldHint:true, so "read-only: returns public data and changes nothing" largely restates structured data. The credit pricing (1 credit per result, minimum 1 per request) is genuinely new behavioral information not available in annotations or schema, and it earns credit — but the description says nothing about rate limits, result caps, or error behavior.

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?

Three short sentences with zero filler; the read-only guarantee and the cost model are both front-loaded where the agent will read them. Nothing in it is redundant or padded.

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 3-parameter tool with no output schema, the description is adequate but thin: it never indicates what a returned user record contains or confirms that paging works via nextCursor. The credit-cost disclosure is a valuable addition, but return-shape information is absent and there is no output schema to compensate.

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%: query operators, the 1–20 count range with a default of 10, and cursor pagination are all documented in the schema. The description adds no syntax, formatting, or operator guidance beyond that, so 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?

The description gives a specific verb and resource ("Search X users"), which is unambiguous on its face. It does not, however, separate this from near siblings such as x_search (tweet search) or x_get_user (lookup by handle), so an agent must infer the distinction from the names alone.

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?

There is no when-to-use guidance and no mention of alternatives — nothing says to prefer x_get_user when the handle is already known, or x_search when the target is posts rather than accounts. The only contextual signal is the tool name itself.

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