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

Goes well beyond the readOnly/idempotent annotations: discloses the 7/30/unlimited window tiers, that truncation is surfaced via since_floor_applied rather than silent, that empty polls are free but still pace-limited, and the credit cost model. It also enumerates the change_type values and explains what close_updated carries.

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 with the core distinction and the cost note, and most sentences earn their place. The cost model is restated twice (the 'COST:' sentence near the top and the closing 'Cost: free with no key...' paragraph), which is the main redundancy dragging it below a 5.

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?

No output schema exists, and the description compensates fully: it describes the unchanged response shape, the row contents, the change_type enum, and the last_close block with its fields. An agent can parse the response and design a polling loop from this text alone.

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 operational meaning the schema lacks: send both next_since and etag together, and an unchanged window yields `unchanged: true` with no rows. The limit parameter is left entirely to the schema, which is acceptable given full coverage.

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 ('return only the funds whose data changed since a given timestamp') and immediately frames the scope as incremental sync rather than discovery. This makes it unambiguously distinguishable from search_funds and get_fund among the siblings.

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?

Explicitly says when to use it ('FOR STAYING CURRENT, not for discovery') and names the alternative it replaces ('Use this instead of re-running search_funds on a schedule. One call here replaces a full re-crawl'). Both the positive case and the anti-pattern are stated.

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