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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is supplied elsewhere. The description usefully adds that results are cursor-paginated, but says nothing about result volume, matching semantics (prefix vs substring vs fuzzy), or what happens with empty queries.

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 short sentences with no waste, and the core purpose is front-loaded ahead of the pagination note. Nothing could be removed without losing 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?

For a simple two-parameter read-only search with a fully documented schema and safety annotations, the definition covers what an agent needs to call it. Without an output schema, it could have said briefly what a user record contains, which is the only remaining 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?

Schema coverage is 100%, so both the query keyword and the cursor semantics (including 'omit or "" for first page') are already fully documented in the schema. "Use cursor to paginate" merely restates the cursor parameter without adding matching behavior or format details, so the 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 by keyword." An agent can tell this is a keyword-based user lookup, but nothing distinguishes it from siblings like batch_get_users_by_ids or check_follow_relationship, so it stops short of full sibling differentiation.

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?

The only guidance is procedural ("Use cursor to paginate"), which tells the agent how to page but not when this tool is the right choice over batch_get_users_by_ids or other user-related siblings. Usage is implied rather than stated.

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