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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so the safety profile is covered. The description usefully adds the returned field set and the server-side time filter, but says nothing about pagination behavior, result caps, or rate limits beyond what the schema already spells out.

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 terse fragments that front-load the resource and its returned fields, then the filter, then the endpoint. No wasted sentences, though the telegraphic style trades a little readability for brevity.

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 a simple four-optional-parameter read tool with full schema coverage, the description covers what is returned and how to filter, which is largely sufficient. It stops short of routing the agent among the many sibling list tools, which is the main completeness gap.

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%, so the schema already documents from, to, page, and limit in detail (ISO 8601 format, defaults, the next_page convention). The description only echoes the from/to filtering, adding no semantics beyond the structured fields. Baseline 3 applies.

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+resource (list all contacts of the account) and enumerates the fields returned (email, name, phone, lists, tags, custom fields, subscription state), plus the endpoint. It does not differentiate itself from close siblings like sendlane_list_list_contacts, sendlane_list_segment_contacts, or sendlane_list_unsubscribed_contacts, so the agent must infer the scope boundary itself.

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 only usage hint is 'Filter by creation time with from/to.' There is no statement of when to choose this over sendlane_get_contact (single record) or the scoped listers (list_list_contacts, list_segment_contacts, list_unsubscribed_contacts), and no exclusions or prerequisites are given.

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