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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the bar is low, yet the description adds real behavior: the exact semantics of reset/breach/overshoot/flat and the carry-over rule for omitted fields. 'Free' signals a cost trait not captured anywhere in structured data.

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 dense paragraph that front-loads the deliverable and then defines each flag inline. Every clause carries information, though the parenthetical flag glossary makes it slightly dense to scan.

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 usefully sketches the return (flags per beat) and the carry-over rule. However, with three optional params it never explains when to pass 'project' versus 'characters', leaving a real ambiguity for a nested-object tool.

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 the baseline is 3, but the description adds a genuine semantic rule beyond the schema: 'Fields a beat leaves out carry over from the beat before', which governs how the nested beat objects should be authored. It does not clarify the project-vs-characters input choice.

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 states a concrete resource and output: a character's arc 'beat by beat' with named continuity flags. The title 'Check a journey' plus the flag taxonomy make the analysis function legible. It does not explicitly differentiate from siblings like atlas_lint or atlas_show, which would be needed for 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?

There is no when-to-use/when-not guidance and no named alternative. The trailing 'Free' hints at a cost tradeoff against a paid sibling (atlas_buy_pack), but the agent is left to infer whether to reach for this over atlas_lint or atlas_show.

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