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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered; the description adds a genuinely non-obvious trait — results are permission-scoped ('each part only where this app may read it'), meaning partial payloads are normal and missing sections should not be read as absence of data. It does not cover failure behavior for an invalid or unknown lead_id, which keeps it short of 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?

Front-loaded with the core value proposition in the first clause, and the second sentence cleanly handles routing. The middle enumeration of returned domains is long and comma-heavy, but it earns its space because no output schema exists — a slightly tighter grouping would raise this further.

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, the description carries the full burden of return-shape disclosure and does so thoroughly, including the permission-scoping caveat. Gaps are minor: no mention of pagination or item caps on the 'latest calls' section, and no error/not-found behavior for an invalid lead_id.

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?

There is a single parameter at 100% schema description coverage, and the schema already explains it is the lead id sourced from search_leads or another answer. The description adds only the implicit notion of 'one merchant' scope, so the baseline 3 applies.

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?

Names a specific verb and resource ('Everything held on one merchant in one read') and then enumerates the concrete content domains returned: contact phones in dial order, status/owner, workspace fields, call facts, tasks, calls, notes, texts, email, bank figures, deals. That granularity makes it unmistakable against siblings like get_call or get_texts, which the description explicitly frames as narrower follow-ups.

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 entry-point rule ('Start here for any question about one merchant') plus a concrete routing rule to alternatives by name (get_call, get_texts, list_lead_emails, get_lead_timeline) for drill-down. The when-to-use and when-to-delegate conditions are both stated rather than inferred.

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