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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world). The description adds two genuinely useful behavioral facts beyond them: search does not consume lead allowances (cost behavior) and phone numbers stay masked until the authorized workflow is used (data-access behavior).

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?

Front-loaded with purpose, then usage trigger, cost note, masking note, and pagination. Four sentences that mostly earn their place, though the enumerated filter list partially duplicates the schema.

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?

Given full annotation coverage, no output schema, and 100% schema coverage, the description is complete enough: it conveys purpose, cost, masking, and pagination. It could still note result ordering or the absence of a required filter, but nothing critical is missing.

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%, so each filter parameter is already documented. The description echoes the filter list and adds pagination context (limit/offset, up to 50 records) but no syntax or format detail beyond the schema, making the baseline 3 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 (Search) and resource (LastDatabase phone lead records) plus the dimensions searched. It implicitly distinguishes itself from siblings like search_consumer_emails and search_hot_leads by naming the 'phone lead' resource, but never explicitly contrasts them.

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?

"Use when the customer requests phone-number lead discovery" gives a clear usage trigger. However, it offers no exclusions or guidance on when to prefer sibling searches such as search_hot_leads, search_mixed_leads, or search_people.

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