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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds substantial context beyond them: the data source and update cadence (daily fca.org.uk file), the aggregation/anonymisation semantics (one row per issuer, no holder names), and the regulatory basis. This is exactly the kind of provenance an agent cannot get from annotations.

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?

Front-loaded with the core purpose, followed by data provenance and filtering rules, then concrete call examples. Information-dense with little waste, though the all-caps emphasis and layered clauses make it slightly heavy for a two-parameter lookup.

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 return-value burden and does provide the shape (one row per issuer, aggregated, no names), which is adequate for this simple read tool. It stops short of naming the returned fields, but an agent has enough to call and interpret it 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 coverage is 100%, so both parameters are documented, but the description adds meaning beyond the schema: issuer is substring and case-insensitive, and crucially that at least one of issuer/ISIN is required even though the schema lists zero required parameters. That mutual-requirement constraint is genuinely useful added value.

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: retrieving current FCA-disclosed net short positions for an issuer. The scope detail (aggregated per-issuer, one row per issuer, no position-holder names, from the daily aggregated-current-net-short-positions file) implicitly and effectively distinguishes it from siblings like fca_largest_shorts and fca_short_changes.

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?

Usage is implied (look up short positions for a given issuer/ISIN) and the constraint that at least one filter is required is stated, but there is no explicit when-to-use guidance and no named alternatives such as fca_largest_shorts or fca_short_changes. The agent must infer which sibling to pick.

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