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

Annotations already declare readOnlyHint, idempotentHint and non-destructive behavior, so the safety profile is covered externally. The description adds nothing beyond pointing at describe_operation; it does not say what associations are returned, whether pagination applies, or what the response shape is.

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?

It is short, but the first sentence is duplicated verbatim and the operation ID is noise for an agent that already has the tool name. The useful content (pointer to describe_operation) is buried at the end.

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 tool with an undescribed nested 'query' object and no output schema, the description should explain what associations are and how to filter them. Instead it defers entirely to describe_operation, leaving an agent unable to predict the response.

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 0% for both parameters. The description only echoes ':id' in the URL, which repeats what the schema's required 'id' already says, and says nothing about the free-form 'query' object or its expected keys.

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 URL path 'GET /api/contacts/:id/associations' conveys a verb (GET) plus a resource (associations for a contact), which does distinguish it from the sibling get_contacts_by_id. However, the description never states in plain language what an 'association' is or what the call returns, so it is only marginally more than a restated route.

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 statement of when to use this tool versus get_contacts_by_id, get_contacts_by_id_custom_fields_values, or any other contacts sibling. The only routing hint is 'describe_operation provides native request schemas', which is about schema discovery, not usage selection.

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