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

With no annotations, the description carries the full burden and delivers: it defines the computation path (base = today's active list members, excluded = filter removals), explains that audience_live_total is TODAY's public, discloses the post-send addition of recipients_snapshot, excluded_on_send (frequency cap and blocked domains) and remaining_to_send, and flags total_recipients as a deprecated alias. That is unusually rich behavioral disclosure.

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 leading question front-loads the purpose and each following clause maps to a distinct return field, so the sentences largely earn their place. It is dense and slightly long, but not padded.

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?

No output schema exists, so the description must describe return values — and it enumerates the key fields and their meaning, plus the pre/post-send distinction and the deprecated alias. For a single-parameter read tool this leaves nothing an agent needs missing.

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 0% and the lone parameter (campaign_id) is undocumented in both schema and description. The description implies a campaign context ('este correo') but never defines the identifier's source or format, so it only partially compensates for the coverage 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?

States a specific action (compute the REAL recipients of a campaign applying the saved filter) and frames it as the send-time path, which cleanly separates it from set_campaign_audience and get_campaign_stats. An agent knows exactly what question this tool answers without opening the schema.

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?

Usage context is implied rather than stated — 'aplicando el filtro guardado' and the pre-send framing suggest calling it before launch_campaign, but there is no explicit 'use this when X, use Y instead' guidance or prerequisite. The behavioral branch (extra fields if sending already started) implies a state but does not say when to prefer it.

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