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

Annotations include readOnlyHint:true, which aligns with the description and reduces the need for extra safety disclosure. However, the description adds no additional behavioral context—such as whether existing query parameters are preserved or replaced, or what the output format looks like. It is consistent with annotations but not richly informative.

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 description is a single, front-loaded sentence that immediately identifies the action and the involved parameters. Every word is necessary; there is no filler, repetition, or unnecessary explanation.

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 description should explain what the tool returns. It only says 'Append...to a destination URL,' implying an output but never explicitly stating it returns the built URL. It also lacks details on edge cases or validation behavior. For a simple tool, this is a notable omission.

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 compensate. It lists the five UTM parameters (source, medium, campaign, term, content) plus the destination URL, which provides some meaning beyond raw property names. However, it does not explain what each parameter represents, which are required vs optional, or provide examples. Standard UTM familiarity may help, but the description alone is insufficient for a new agent.

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 clearly states the tool's function: 'Append UTM tracking parameters...to a destination URL.' This is a specific verb+resource combination and obviously distinguishes it from the many generator/calculator siblings. The list of parameters further clarifies its scope.

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 provides no guidance on when to use this tool versus alternatives, nor any prerequisites or exclusions. It merely states what it does. With many sibling tools like ad-copy-generator or meta-tag-generator, there is no explicit positioning or use-case context.

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