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

Goes well beyond the readOnly/destructive annotations by disclosing the exact data-masking behavior: tax file, national insurance, IRD/NRIC numbers, bank accounts and super member numbers are removed. That redaction notice is critical for an agent reasoning about whether this tool returns sensitive fields, and the underlying endpoint path is also given.

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?

Front-loads the core purpose, then the field inventory, then the redaction caveat, then the endpoint. The field list is long but earns its place given there is no output schema; nothing is redundant.

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?

With no output schema, the field enumeration and the explicit statement of what is stripped make the return shape predictable, which is the main gap this tool had to close. Minor omissions remain (no pagination/auth notes, no error semantics), but they are low-impact for a simple single-record read.

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?

Both parameters are fully documented in the schema (100% coverage, including provenance hints from keypay_list_businesses and keypay_list_employees). The description adds no parameter meaning of its own, 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?

States a specific resource and scope ('One employee's full record') and enumerates the fields returned, which makes the read-one-employee purpose unambiguous. It is distinguishable from keypay_list_employees by the singular scope, though it never names that sibling 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?

Usage is only implied: fetching a single employee's record by id. There is no statement of when to prefer this over keypay_list_employees or keypay_get_user, nor any prerequisite or exclusion. The schema descriptions do point at keypay_list_employees as the id source, but that lives in structured data, not the description.

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