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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds value by naming the returned fields (status, objective, budget, schedule), but says nothing about auth requirements, rate limits, or behavior when the id is unknown.

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?

A single tight sentence with the action and lookup key front-loaded and the payload summarized in a parenthetical. No filler or redundancy.

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 single-parameter read whose annotations cover the safety profile, the description is nearly sufficient; listing the returned fields compensates for the absence of an output schema. Only the missing error/not-found behavior keeps it from being fully complete.

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?

Only one parameter and schema description coverage is 100%, so the schema fully documents campaign_id. The description adds no format, prefix, or validity information beyond the phrase 'by id', making the baseline 3 correct.

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 (Get) and resource (one Meta campaign) with the lookup key (by id) and enumerates the salient fields returned. It is clearly distinguishable from meta_ads_list_campaigns (plural/list) and from meta_ads_get_ad / meta_ads_get_ad_set by naming the campaign entity.

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: fetch a single campaign when you have its id. There is no guidance on when to prefer meta_ads_list_campaigns or meta_ads_insights instead, and no prerequisites mentioned. Minimum viable routing information only.

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