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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so safety needs no restating. The description adds genuinely non-structured context: the billing model ('charging per lead added') and the exact response fields (status, cadence, per-run cap, leads added so far, last and next run, target list), which lets an agent decide whether this call answers its question. Pagination or result-count limits are not mentioned, which keeps it from a 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 sentences, zero filler. The identity and terminology mapping come first, then the returned fields, then the sibling handoff — a logical front-loaded order with every clause carrying information.

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?

With no output schema, describing the returned fields is exactly the missing piece, and the description supplies it along with the cost model and the mutation alternative. Only the absence of any pagination or result-volume note for what could be an unbounded account-level list keeps it from 5.

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 description coverage is 100% and the single optional status enum is fully documented in the schema. The description never mentions the status filter, so it adds no meaning beyond structured fields; the baseline 3 for a fully covered schema 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 verb and resource ('List the account's lead feeds') and immediately disambiguates the naming clash with the dashboard term ('Targeted Leads, called Lead Feeds in the dashboard'). It also defines what a lead feed actually is (recurring searches that add leads daily or weekly), so an agent can distinguish it from list-mailing-lists, create-lead-feed and buy-targeted-leads without opening schemas.

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 routes state-changing intent to the sibling: 'Use update-lead-feed to pause, resume, stop or change one.' That is clear when-not-to-use guidance for the main alternative an agent would confuse it with. It does not mention create-lead-feed for creation or say anything about when listing is unnecessary, so it falls just short of full when/when-not coverage.

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