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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: pricing ('Paid per call from your Stratum API balance, or use a test key') and the shape of the result. It omits result limits or pagination behavior for a broad name match.

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?

Two sentences, zero waste, with the operation and return content front-loaded and the billing note last where it belongs.

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?

For a one-parameter read tool with no output schema, the description covers what it does, what it returns, and the cost model. Only matching semantics (partial vs exact) and any result cap are left unstated.

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 the name parameter's meaning and 2-character minimum are already documented. The description only restates 'by firm name', adding no syntax or matching-behavior detail (exact vs partial match) beyond the schema.

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 (search) and resource (FCA Financial Services Register) scoped to firm name, and tells the agent what comes back (FRN and status). It doesn't name the sibling fca_firm, so an agent must infer the search-vs-lookup split, which keeps it short of a 5.

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 by 'by firm name' — an agent with a name in hand knows to call it — but there is no explicit when-to-use framing and no routing to fca_firm for callers who already have an FRN. Minimum-viable guidance.

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