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

Annotations already cover the safety profile (readOnly, non-destructive), and the description adds substantial semantics the annotations cannot: registers are never summed, values are percentage points of issued share capital, these are dated disclosures rather than live positions, and unmatched/stale registers are named at the end. It also pre-empts the 'no row = zero' misreading, which is exactly the kind of trap this tool needs to disclose.

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?

A single dense paragraph, but it is front-loaded with the identifier format and scope before moving to caveats, and every clause carries distinct meaning. It is long, though a few clauses (the full register list) could be trimmed without loss.

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?

With no output schema, the description carries the burden of describing returns and does so: percentage points of issued share capital, one row per register, and unmatched registers named at the end. Nothing needed to call or interpret the tool is missing.

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% and both parameters are self-documented, so the description's MIC:TICKER examples and bare-ticker fallback largely restate the schema. Baseline 3 is appropriate since the schema does the heavy lifting.

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?

States a specific verb and resource ('net short positions disclosed to European regulators') plus a precise scope ('one listing outside the US'). It also explicitly separates itself from the US counterpart 'For US listings use GetShortInterest', so an agent can route without opening the schema.

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?

Gives both when-to-use (non-US listing, registers by MIC:TICKER/ISIN/LEI) and when-not ('For US listings use GetShortInterest'), and contrasts against adjacent concepts the agent might otherwise confuse it with: total short interest, current holdings, short volume.

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