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 two genuinely useful behavioral facts beyond that: results are paged and default ordering is newest first. It stops short of pagination limits, whether a total count is returned, or what a page contains.

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 short sentences, no filler, and the core capability is front-loaded before the filtering detail. Every clause earns its place.

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?

There is no output schema, so the description is the only place an agent could learn what a lead record contains and how pagination metadata is expressed — and it doesn't say. For a 10-parameter list tool with 20% schema coverage, the definition is serviceable but leaves the return contract undefined.

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 only 20%, so the description carries real weight here, and it does map the filter families (list, label, status, verification, ESP) onto the corresponding parameters and clarifies that search spans email, name and company. Gaps remain: multi-value filters are not described as OR vs AND, and the sort/pageSize defaults and bounds are left entirely to the schema.

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?

Specific verb + resource ("List leads") plus the filter dimensions available, so an agent immediately knows this is the read path for lead records. It is distinguishable from siblings like list_lead_lists or import_leads by resource, though the description never explicitly names the boundary.

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 by naming the filter axes, which tells an agent this is how to retrieve a filtered lead set, but there is no explicit when-to-use / when-not guidance and no pointer to a sibling for the adjacent cases (listing lists, importing leads). Nothing is misleading, but nothing is deliberate either.

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