Apollo MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool adds contacts to an email sequence, implying a write operation, but doesn't disclose critical behaviors: whether this triggers immediate emails, requires specific permissions, has rate limits, handles duplicates, or what happens if the sequence is inactive. For a mutation tool with zero annotation coverage, this leaves significant gaps in understanding how the tool behaves.

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 efficiently structured: a clear purpose statement followed by Args and Returns sections. Every sentence earns its place—the purpose is front-loaded, and the parameter/return explanations are concise without redundancy. There's no wasted text, making it easy for an agent to parse quickly.

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?

Given the tool has an output schema (which covers return values) but no annotations and 0% schema description coverage, the description is moderately complete. It explains the basic operation and parameters, but as a mutation tool, it lacks details on behavioral traits (e.g., side effects, error conditions) and usage context. The output schema handles return values, but the description doesn't address other complexities like authentication needs or idempotency.

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. It lists all three parameters (sequence_id, contact_ids, email_account_id) and provides basic semantics: sequence_id identifies the target sequence, contact_ids are the contacts to add, and email_account_id is optional for sending. However, it doesn't explain parameter formats (e.g., UUIDs), constraints (e.g., maximum contact_ids), or the implications of omitting email_account_id. The description adds value but doesn't fully compensate for the lack of schema descriptions.

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 ('Add contacts') and resource ('to an email sequence'), making the purpose immediately understandable. It distinguishes itself from siblings like 'list_add_contacts' (which adds to lists) and 'contacts_search' (which searches contacts) by specifying the email sequence context. However, it doesn't explicitly differentiate from 'sequence_activate' or 'sequence_create', which also involve sequences but perform different actions.

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?

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., whether the sequence must be active), exclusions (e.g., cannot add contacts already in the sequence), or when to choose other tools like 'sequence_create' (for creating sequences) or 'list_add_contacts' (for adding to lists instead of sequences). The agent must infer usage from the tool name alone.

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