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

readOnlyHint=true already tells the agent this is a safe read, so the description owes nothing about mutation risk, but it also adds no behavioral context of its own: no mention of pagination behavior, default sorting, whether an empty result is an error, or what happens when id matches nothing. The only behavioral content (default limit 50, clamping, '-' descending prefix) already lives in the schema.

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?

A single front-loaded sentence with no filler; the mode-selection rule comes before any detail. Nothing in it could be removed without losing 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?

For a six-parameter, read-only, object-filtered query tool with no output schema, the description is minimally adequate: it covers the two access modes but says nothing about the shape of results or how query/fields/sort interact. The high schema coverage limits the damage, but an agent still lacks a picture of what comes back.

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 83%, so the schema baseline already carries most parameter meaning and a 3 is appropriate. The description does not compensate for the one undocumented parameter (fields) and simply echoes the id-vs-query distinction the schema already states.

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?

The description uses a specific verb ("Find") plus the exact resource ("LimMailDomain records") and outlines the two access modes. Sibling differentiation is largely carried by the resource name itself (each query_lim* targets a different collection), so no explicit sibling routing is needed, but a reader gets no hint of what a LimMailDomain actually represents.

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?

"Pass id for one record, or query for a filtered list" tells the agent which parameter selects which mode, which is real usage guidance. However, this is a restatement of the id parameter's schema description ("Fetch one record by id; omit to query many"), and there is no guidance on pagination strategy, when to combine query with sort/limit, or when to reach for a different tool.

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