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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the underlying REST route and the grant-scoping behavior, but says nothing about pagination semantics, default/max page size, or result ordering for a list operation.

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 sentences, front-loaded with the primary purpose; the endpoint reference is compact and useful for API-aware agents, though it is close to redundant with the tool name.

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 no output schema, the description should at least hint at return shape and pagination behavior, since page_token/limit are exposed. The grant-scoping note is helpful, but pagination and default limit behavior are left entirely unaddressed.

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 all five parameters (email, limit, grant_id, page_token, phone_number) are already documented in the schema. The description only echoes the two filter parameters and adds no format or interaction detail beyond the schema.

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 ('List contacts for the connected account') plus the optional filtering scope, which is more than a restatement of the title. It does not explicitly differentiate from the closest sibling, nylas_get_contact, which retrieves a single contact.

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 mention of 'optional email/phone filters' implies when the tool is useful, but there is no explicit guidance on when to prefer it over nylas_get_contact, nor any note about paginating through results. Usage is inferable but not stated.

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