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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds genuinely non-redundant context: the underlying API call is a POST that is semantically read-only purely because of the id list. That preempts an agent misreading a POST as a mutation. It doesn't cover return shape or partial-failure behavior for invalid uids, keeping it below 5.

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, no waste, with the capability and the returned metrics front-loaded before the POST clarification. Every clause earns its place.

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 one-parameter read tool with no output schema, the description names the exact metrics returned and explains the misleading HTTP verb, which is what an agent needs to call and trust it. Minor gaps remain around error behavior for bad uids and ordering of results.

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% and the single parameter campaign_uids is fully documented including min/max item counts. The description reinforces the 50-item cap and the id-list nature but adds no syntax or format detail beyond the schema, so 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 ('Bulk report summary ... for up to 50 campaigns in one call') and enumerates the returned metrics (sent, opens, clicks, bounces, unsubscribes). The word 'Bulk' and 'in one call' implicitly contrast with the single-campaign sibling get_campaign, though no sibling is named explicitly.

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 is implied rather than stated: the 'up to 50 campaigns in one call' framing suggests this is the batching alternative to per-campaign calls, but there are no explicit when-to-use/when-not rules or named alternatives. An agent can infer the context but must do so itself.

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