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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely non-obvious context beyond that: link clicks are NOT tracked in this version (only pixel opens), and that 'bounces' means confirmed hard bounce. That materially changes how an agent should interpret the numbers.

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?

Front-loaded label, then purpose and metric list, then the usage cue and the tracking caveat — good ordering with no filler. The emoji-headed label and warning glyph are stylistic overhead but the sentences themselves all carry information.

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 compensates by enumerating the returned metric categories, which is exactly what an agent needs to interpret results. The only remaining gap is how these numbers relate to the enrollment-counting siblings, which is left for the agent to infer.

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% and both parameters are described in the schema (sequence_id obtained via list_sequences; target_user_id admin-only with a default). The description adds only the emphasis on a single cadence and no parameter-level detail, so the baseline 3 for a fully documented schema 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?

It states a specific verb (compute performance metrics) and a precisely scoped resource: ONE cadence, with the exact metrics enumerated (per-step sends, email opens, confirmed hard bounces, unsubscribes, replies, completions). An agent can tell it apart from list_sequences/create_sequence, though it does not explicitly differentiate itself from count_enrollments or list_enrollments, which cover adjacent territory.

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?

It gives concrete decision contexts: check before releasing a larger batch, or to measure the real result of a cadence already running. That is a clear use case, but there are no explicit exclusions or pointers to sibling tools (list_sequences is only referenced inside the schema, and count_enrollments is never mentioned).

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