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

Annotations already declare readOnly/idempotent/non-destructive, yet the description still adds substantial behavior: newest-first ordering, an explicit page ceiling of 'at most 25,000 characters' (so a page may return fewer than limit), the rule that next_cursor is meaningful only while has_more is true, and the existence of pagination.omitted for oversized numbers. These are non-obvious traits an agent cannot get from structured fields.

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 sentences, none wasted, with the bounded-pagination constraint front-loaded before cursor semantics. It is dense but every clause carries operational information; a slightly shorter phrasing of the 25,000-character rule could tighten it further.

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 usefully documents the return envelope (pagination.next_cursor, has_more, omitted) that the agent must read to page correctly. The remaining gap is project_id and any scoping behavior beyond organization_id, which is only partially covered in the schema.

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 only 50%, but the description compensates by clarifying that limit is a true upper bound rather than a guaranteed count, and by tying cursor to pagination.next_cursor. project_id remains completely undocumented in both the schema and the description, leaving one gap.

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?

Names a specific verb and resource ('List one bounded, newest-first page of the workspace's phone numbers with registration status'), and the possessive 'workspace's' implicitly distinguishes owned numbers from the catalog tool. It never names a sibling explicitly, so an agent must still infer the boundary versus get_number_catalog or list_phone_servers.

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 description explains pagination mechanics but gives no when-to-use, when-not-to-use, or alternative-tool guidance. An agent is not told how this list differs from get_number_catalog or get_number_rules, which is the primary routing decision for this tool.

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