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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral facts: results are ordered newest first, each entry carries a source_url, and the call is free at 100 calls/day without a key — a rate-limit disclosure the annotations don't supply. It does not say what happens on an unbounded `since` or whether results are capped by anything other than `limit`.

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 trigger, then the return shape, then filters, then cost — no filler. The inline JSON example for `since` earns its characters by disambiguating the date format.

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?

Output schema exists, so return values needn't be spelled out further, and the description still tells the agent the ordering. Combined with annotations and the cost note, an agent has enough to call this correctly; only the meaning of `slug` and any pagination behavior are left implicit.

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 50% schema coverage and no descriptions on `kind` or `slug`, the description does compensate somewhat by naming all four as filters and giving a concrete `since` example. However it never explains what `slug` identifies (a business slug, presumably) and does not map the enum values to the change types with any precision beyond the prose list.

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 change log of AI startup revenue data, newest first — and names the exact record types (businesses added, figures added/revised/re-dated/removed). No sibling in the list is a changelog tool, so an agent can route to it unambiguously.

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?

"Use when the user asks what is new or what changed recently" gives an explicit trigger condition that maps directly to user phrasing. It stops short of naming when *not* to use it or pointing to an alternative (e.g. vs. leaderboard or get_business for current values), so it misses the 5 bar.

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