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

Annotations already cover safety (readOnly, idempotent, non-destructive), and the description adds substantive behavior: tier gating, redacted snapshots plus an upgrade pointer on the free tier, and the downsample 'latest snapshot per bucket wins' rule. It stops short of describing pagination or result volume limits.

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?

Three dense sentences, front-loaded with tier gating and the core return, then filters. Every clause carries information, though the filter sentence packs five concepts and is heavy to parse.

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 an 11-parameter read tool with no output schema, the description covers the notable behaviors an agent needs: tier gating, redaction, filter semantics, and downsample rules. Remaining gaps are the response shape details and pagination/volume expectations.

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?

With 73% schema coverage the schema already documents most parameters, yet the description adds value beyond it: it clarifies the relative offset syntax ('-3h' or '0'), the absolute-vs-relative pairing, the interval enum, and the exact semantics of changes_only ('drop unchanged adjacent snapshots'). That goes past restating the schema.

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?

States a specific verb and resource: 'Returns the historical line-movement snapshot series for an event', including the granularity (every recorded price/point change per outcome). It does not, however, differentiate itself from close siblings like propline_get_event_movement or propline_get_odds_closing, so an agent must infer the split.

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 'Hobby+ endpoint' note and the free-tier redaction behavior are useful prerequisites, and the filter options imply intended usage. But there is no explicit when-to-use/when-not guidance nor any pointer to an alternative sibling, which is what an 11-parameter, multi-purpose tool most needs.

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