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

No annotations are present, so the description carries the full burden. It does disclose the key behavioral trait — this is a mutation that both adds and removes depending on state — but says nothing about authentication requirements, failure modes, or edge cases such as toggling a nonexistent slug. The output schema covers return values, so this is a partial but not complete disclosure.

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 eight-word sentence that front-loads the verb and wastes no words. Every element earns its place, and the description is appropriately sized for the tool's simplicity.

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 one-parameter tool with 100% schema coverage and an output schema, the description covers the core facts needed to invoke it correctly. The gaps are the absence of usage context and behavioral caveats (auth, error behavior), which makes it adequate but thin.

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 baseline is 3. The description adds no parameter-level detail beyond what the schema already provides; 'adds or removes' closely parallels the schema's '(marks it or unmarks it)', so no compensatory value is added.

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 uses specific verbs ('adds or removes') with a concrete resource ('a template from favorites'), making the toggle action unambiguous. It inherently distinguishes itself from read-only siblings like my_favorites and from add_to_cart, since the action and target resource are clearly stated even without naming an alternative.

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?

No when-to-use guidance, exclusions, or prerequisites are provided. An agent receives no help deciding between this tool and alternatives, though the conflict with siblings like my_favorites is minor given the differing action.

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