add_equation

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

Annotations already declare a non-readonly, non-idempotent, non-destructive mutation. The description adds context beyond them by disclosing that the call triggers a rebuild — a meaningful side effect on the model — and by spelling out the required string syntax. It stops short of saying what happens on a duplicate name or an invalid expression.

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?

The action and its side effect lead, followed by two compact examples that each teach a distinct mode. Every sentence earns its place and nothing is 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?

With an output schema present, return values need no explanation, and the description covers syntax, semantics and the rebuild side effect for a single-parameter mutation. It could be stronger by noting failure modes (bad syntax, duplicate variable name) that an agent should anticipate.

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 0%, so the description must carry the single parameter, and it largely does: double-quoted names, the two accepted expression shapes, and the unit-defaulting rule for bare numbers. Only edge details (escaping, explicit units, multiple statements) are left implicit.

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?

Specific verb plus resource ('Adds a global variable or an equation'), with the two supported modes spelled out and each illustrated by a concrete example. An agent can immediately tell this apart from get_equations and delete_equation in the sibling list.

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 distinguishes the two forms of input (global variable vs. dimension-driving equation), which is useful context, but it never states when to reach for this tool versus set_dimension or add_sketch_dimension, nor any preconditions (e.g., an open document). Usage is implied rather than guided.

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