IG Trading MCP

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

With no annotations provided, the description carries the full burden of behavioral disclosure but offers minimal information. It states the action ('Login') but doesn't describe what happens on success (e.g., session token creation, persistence), failure modes, rate limits, security implications, or whether this is a one-time or recurring operation. For an authentication tool with zero annotation coverage, this leaves critical behavioral traits unspecified.

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, focused sentence with zero wasted words. It's front-loaded with the core action and resource, making it immediately scannable and efficient. Every word earns its place by conveying essential purpose without redundancy or fluff.

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 complexity of an authentication tool with no annotations and no output schema, the description is insufficiently complete. It doesn't explain what the tool returns (e.g., session tokens, account status), error behaviors, or how login state integrates with other IG tools. For a critical security-related operation, more context is needed to guide safe and effective use.

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 100%, so the schema fully documents all 5 parameters (apiKey, identifier, password, isDemo, useEncryption) with descriptions and defaults. The description adds no parameter-specific information beyond implying authentication credentials are involved. This meets the baseline of 3 since the schema does the heavy lifting, but the description doesn't enhance understanding of parameter roles or interactions.

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 verb ('Login') and resource ('IG Trading account'), making the purpose immediately understandable. It distinguishes this from sibling tools like ig_logout, ig_get_accounts, and ig_switch_account by focusing specifically on authentication. However, it doesn't explicitly differentiate from potential alternatives or clarify if this is for initial session establishment versus re-authentication.

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 it must be called before other IG tools), when not to use it (e.g., if already logged in), or how it relates to sibling tools like ig_switch_account for account management. 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.