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

No annotations exist, so the description must carry the behavioral load; it does disclose the latest-file default and an authentication prerequisite (subscriber key), which are genuinely useful. It says nothing about volume, pagination, or what an empty day returns, which matters for a retrieval tool whose result set size is controlled by '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?

The payload contents are front-loaded in the first clause, followed by two short operational notes. Dense but readable, with no filler sentences; only the slightly promotional phrasing ('every contact path') costs it a point.

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 three optional parameters, full schema coverage, and no output schema, the description usefully sketches the returned fields and the auth requirement. It still leaves the relationship between 'date' and 'latest file' and the behavior at the limit boundary unexplained, so an agent cannot fully predict the response.

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 date format, need enum values, and the 1-200 range are already documented in structured fields. The description's 'Defaults to the latest file' duplicates the schema default rather than adding new semantics for any of the three parameters.

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 names the resource and its scope ('the leads for one day') and enumerates the payload it carries (need, opener, contact paths), which is more informative than a bare name. It does not, however, distinguish this from the sibling 'lead' or 'sample_leads' tools, leaving the agent to guess which one returns the full daily set.

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?

'Defaults to the latest file' implies the common no-argument call and 'Needs the subscriber key' signals a prerequisite, so usage is partially inferable. There is no explicit when-to-use versus 'lead' or 'sample_leads', and no guidance on when to pass a date versus relying on the default.

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