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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so safety is covered. The description adds genuinely non-schema context the agent can't get elsewhere: 'Not metered. Available without an account.' — i.e. no cost and no auth prerequisite, which affects whether the agent should call it freely to clarify terms. It stops short of describing lookup-miss behavior.

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?

One sentence plus two short factual clauses; the glossary tag and core purpose are front-loaded, and the cost/auth facts earn their place because they change calling behavior. Slightly awkward phrasing ('the desks return') costs a little clarity but not length.

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?

A single-parameter, output-schema-backed lookup: return values need no explanation, and the description covers what it does, what terms qualify, cost, and auth. Only gaps are unknown-term behavior and whether matching is exact or case-insensitive, which are minor for a glossary tool.

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% for the single 'name' parameter, so the schema already carries the semantics, and the term examples in the description duplicate those in the schema. Baseline 3 applies; the description adds no case-sensitivity or alias guidance 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+resource: returns the fAlpha definition of a term, and frames it as 'a term the desks return', which distinguishes it from the sibling desk tools that produce data rather than definitions. The concrete term examples (EI, Sharpe, term structure) make the resource unambiguous, though it never explicitly frames itself as 'the glossary lookup, not a data tool'.

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?

'a term the desks return' implicitly tells the agent to come here when it encounters unfamiliar jargon in output from the desk tools, which is a real usage pointer rather than none. It does not state exclusions (e.g. don't use it to look up tickers or non-fAlpha terms) or what happens on an unknown term, so the routing guidance is clear but not exhaustive.

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