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

readOnlyHint=true already declares the safety profile, so the description's burden is light. 'Get one ... by its ID' usefully adds that the result is a single entity rather than a collection, but it says nothing about what happens when the ID does not exist or what fields are returned.

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. It is efficient, though arguably too terse for a tool that lacks an output 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?

For a one-parameter read-only getter this is close to adequate: the action, target, and key are all present. Missing is any notion of not-found behavior or expected return content, which matters somewhat because no output schema exists.

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?

The schema has one required parameter with 0% description coverage, so the description must carry the meaning. 'By its ID' tells the agent the parameter is the client identifier, but adds no format hints (ID shape, string length/lookup rules) beyond what the schema name 'id' already implies.

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 names a specific verb and resource ('Get one Hub Planner client') and states the lookup key (ID), which separates it from the list/search siblings. It stops short of explicitly naming those siblings, but the single-vs-many distinction is clear.

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?

There is no guidance on when to use this versus hubplanner_list_clients or hubplanner_search_*; the only implied rule is 'when you have an ID'. No prerequisites, no exclusion for the case where the ID is unknown.

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