cpu_write_register

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

Annotations supply only readOnlyHint=false, i.e. 'this mutates'. The description adds genuine behavior beyond that: segment registers 'update the cached physical base', a non-obvious side effect an agent would not infer otherwise. It stops short of noting reversibility, permissions, or error behavior, so not a 5.

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, front-loaded with the action, then the two register classes. Every sentence carries information and nothing is padded or repeated.

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 two required parameters, no nested objects, and no output schema, the description covers what is needed: the operation, the accepted values per class, and the segment-base side effect. Minor omission of any failure/validation behavior keeps it from a 5.

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%, so the schema already documents both 'value' and 'register', including the register enumeration and value ranges. The description's bit-width rules largely restate the schema, 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?

States a specific verb+resource ('Write a CPU register') and even splits the resource into two register classes with their widths. Clear on its own, but it never distinguishes itself from adjacent write tools in the sibling list such as mem_write or port_write, so an agent gets no explicit routing signal.

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: the register lists tell you what it operates on, but there is no statement of when to reach for this instead of mem_write/port_write or any prerequisite context. No exclusions or alternatives are offered.

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