Single position by ticker

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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds valuable context beyond annotations: it fails if no position exists, clarifies that the ticker must be exact (including suffix), and implies the scope is open positions only. This enriches the agent's understanding.

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 three short sentences: the first states the action, the second provides usage guidance with alternatives, and the third notes the failure condition. Every sentence earns its place with no wasted words.

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?

Despite having no output schema, the tool is simple and the description covers its core purpose, when to use it, and edge-case behavior. Annotations handle safety aspects, so the description is complete for effective selection and invocation.

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 input schema fully describes the ticker parameter (100% coverage), so the baseline is 3. The description goes beyond the schema by giving a concrete example and explicitly contrasting it with the plain ticker form, adding semantic clarity that helps the agent avoid common mistakes.

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 it returns one open position by exact Trading 212 ticker, and distinguishes itself from sibling tools by explicitly naming the alternatives and providing a concrete ticker example (AAPL_US_EQ, not AAPL). This is a specific verb+resource with strong sibling differentiation.

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 explicitly states when to use this tool ('Only use this when you already know the exact ticker') and provides clear alternatives ('otherwise call t212_list_positions... or t212_search_instruments'). This is a textbook example of usage guidance with exclusions.

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