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

Annotations only declare the safety profile (not read-only, not idempotent, not destructive); the description adds the behavior that actually matters: rows lacking both a profile URL and an email are dropped silently, the import is asynchronous, and the campaign is not launchable until isFiltered flips true. That silent-skip and blocking-state disclosure is exactly the kind of context annotations cannot carry.

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?

Four sentences, zero filler, front-loaded with purpose then field mapping then edge-case behavior then routing. Each sentence carries distinct information an agent needs.

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 4-parameter mutation with no output schema, it covers async behavior, silent-skip rules, the launch-blocking flag, and sibling routing. The remaining gap is what the call returns (imported vs skipped counts, job handle for polling) — with no output schema, a hint there would close the loop.

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%, so the baseline would be 3, but the description adds genuine value the schema lacks: the header schema declares additionalProperties:false without enumerating permitted target fields, and the description supplies the full list (profileUrl, salesNavUrl, recruiterUrl, email, firstName, lastName, fullName, personalization, phone, website, customVariable). It does not explain removeDuplicates semantics, which keeps it from a 5.

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 and resource: "Bulk-load prospects into a campaign from parsed CSV rows." It immediately distinguishes itself from campaign_add_prospects and campaign_set_source, so an agent can pick 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?

Explicitly gives the selecting condition ("Use this when the user has a list in hand") plus two exclusions with named alternatives: audience-described cases go to campaign_set_source (built via search_url_build), and already-running campaigns go to campaign_add_prospects. When-to-use, when-not-to-use, and alternatives are all present.

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