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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is lower. The description adds one genuinely useful non-annotation fact — a master API key is required — plus pricing context, but omits the behavioral trap that unfiltered calls fail with HTTP 400.

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?

Two short, front-loaded sentences with no wasted prose; the auth requirement is stated immediately. The injected pricing comment block adds bulk but is boilerplate rather than authored content.

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?

An output schema exists, so return values need no explanation, and the schema carries the filter requirement. Still, for a 10-parameter retrieval endpoint with several near-identical siblings, the description is thin — it never mentions filtering, pagination, or how it differs from neighboring search tools.

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 description coverage is 100% across all 10 parameters, so the schema already documents each filter and the at-least-one-filter rule. The description contributes no parameter meaning beyond that, making the baseline 3 appropriate.

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 ('Get a list of notes'), which is clear on its own. It does not, however, distinguish this tool from the many other Apollo list/retrieval siblings (e.g. get_apollo_emailer_messages_search, get_apollo_users_search), so an agent cannot tell from the text alone why it would pick this one.

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 guidance, no mention of alternatives, and no hint about the most important usage constraint: that at least one filter argument is required. The only guidance an agent gets is buried in the schema, not the description.

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