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

readOnlyHint already declares this is a safe read, so the description's added value is limited to the exact-match semantics and the 'GET /lookup' endpoint hint. It says nothing about what a hit looks like, whether all matching modules are returned, or behavior when nothing matches.

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, front-loaded sentences with the key constraint ('exact') early. The trailing 'GET /lookup' is low-value implementation detail for an agent but costs little.

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 read-only lookup with no output schema, the definition should at least hint at result shape (matched records per module, empty result behavior). It stops short, leaving the agent to inspect the response by trial.

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 type/value/modules are fully documented including enum, length bounds, and default modules. The description only reinforces 'exact' matching and 'one or more modules', adding marginal meaning beyond 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?

States a specific verb and resource (find records), the searchable modules, and the two lookup keys (exact email or phone). The 'exact' qualifier separates it from a general query tool, though it never names the sibling it supersedes.

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 'exact email address or phone number' versus broader search siblings like vtiger_query or vtiger_list_records, but no when-to-use/when-not or alternative is stated explicitly.

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