set_parameter

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

Annotations already declare a non-read-only, idempotent, non-destructive mutation. The description goes beyond that by disclosing the key side effect ('Fusion recomputes the model') and the return payload (old and new values), which an agent needs to sequence calls. It omits failure behavior for invalid expressions, so it is strong but not exhaustive.

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?

A single front-loaded sentence with the verb first, a parenthetical example for the expression format, and the recompute/return consequence last. Nothing 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 only two fully documented parameters and an output schema present, the definition covers what an agent needs: what is changed, that the model recomputes, and that old/new values come back. The only gap is error handling for an invalid expression, which is minor.

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 parameters are already documented, including an 'as returned by list_parameters' note on name. The description's expression examples largely duplicate the schema's examples, adding little new semantics; 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 and resource ('Change a parameter's expression') with concrete examples, making it obviously distinct from list_parameters and get_design_info. Sibling differentiation is implicit rather than explicit, which keeps it just short of a 5.

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 description implies the use case (setting a new expression on an existing parameter) but never states when to use it versus alternatives such as reading parameters via list_parameters, nor any prerequisites. Usage is inferred rather than guided.

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