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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds value beyond that by disclosing that entries are chronological and attributed to the actor ('written by whoever made them'), which is what makes it an audit trail. It stops short of stating retention window, pagination, or volume caps for a log that could be long.

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 sentences, front-loaded with the core definition and the event list before the exclusion. Dense but every clause earns its place; the em-dash parenthetical could be tightened slightly, but nothing is redundant.

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-only, non-open-world log tool with no output schema, the description covers what the resource is, what an entry represents, and who authored it. It does not describe the entry shape (timestamp/actor/event fields) or result size, which would help since there is no output schema, but the essential calling information is present.

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?

With a single parameter and 100% schema description coverage (campaignId, sourced from `campaign_list` or `campaign_create`), the schema carries the full burden. The description adds no further detail about the id format or how missing/invalid ids behave, so baseline 3 is appropriate.

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 resource and scope: a chronological record of everything that happened to a campaign, with an enumerated list of event types (created, started, paused, resumed, lead sources added, settings changed, limits hit). It also draws a hard line against prospect-level history, naming the sibling tools that cover that instead, so an agent can distinguish it without opening any 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?

Gives an explicit use case: 'the audit trail to read when a user asks why a campaign stopped or who changed a limit.' It also names the negative case and routes to alternatives (`activity_list`, `lead_get`, `sequence_step_stats`). Both when-to-use and when-not-to-use are present.

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