HubSpot MCP

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

With no annotations provided, the description carries full burden but only states the action without behavioral details. It doesn't disclose whether this is a mutation (implied by 'Subscribe'), what permissions are required, if it's idempotent, what happens on success/failure, or any rate limits. This leaves significant gaps for an agent to understand the tool's behavior.

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?

The description is a single, clear sentence with zero wasted words. It's front-loaded with the core action and target, making it immediately understandable without unnecessary elaboration.

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 mutation tool with 3 parameters (one with complex enums), 0% schema coverage, no annotations, and no output schema, the description is inadequate. It doesn't explain the operation's effects, parameter meanings, return values, or error conditions, leaving the agent with insufficient context to use the tool correctly.

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%, so the description must compensate but provides no parameter information. It doesn't explain what 'contactId' represents, what the legal basis parameters mean, or why they might be required. The description adds no value beyond what the bare schema provides, failing to address the coverage gap.

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 clearly states the action ('Subscribe') and target ('a contact to all email communications'), making the purpose immediately understandable. However, it doesn't differentiate from sibling tools like 'communications_update_preferences' or 'communications_update_subscription_status' that might handle similar subscription operations with different scopes or methods.

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?

No guidance is provided about when to use this tool versus alternatives like 'communications_update_preferences' or 'communications_unsubscribe_contact'. The description doesn't mention prerequisites, such as needing a valid contact ID, or contextual factors like whether this overrides existing preferences.

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