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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower, yet the description adds real behavior: the ranking of match types, the accepted character set for q, that a leading $ is ignored, and the auth scope (api:read). It stops short of stating pagination/truncation behavior when limit caps at 25, which keeps it off a 5.

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?

Four dense sentences, each doing distinct work: scoping, match algorithm, query format, return fields, use case, exclusions, auth. The scope and search semantics are front-loaded before the routing guidance.

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?

No output schema exists, and the description compensates by enumerating the returned item fields (symbol, chartDataset, summaryDataset, exchange, securityType, securitySubtype, instrumentClass, lastSeenAt). With universe boundaries, auth requirement, and next-step routing all present, an agent has everything needed to call 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 only 50% (q has no description, limit only carries 'default 12'), and the description fully compensates for q — ticker fragment, allowed characters, leading-$ normalization. limit is left to the schema's default annotation, so one parameter remains unexplained in prose.

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) over a precisely bounded resource (US-equity reference universe = active EQUS.MINI listings), and even specifies the match ordering: exact, then prefix, then contains. Siblings are named in negative space (scan_markets for crypto/HIP-3 perps, get_symbol_research for next step), so the agent can distinguish it without opening schemas.

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 an explicit use case — 'confirm a ticker before get_symbol_research' — plus an explicit exclusion with a redirect: 'Crypto and HIP-3 perps are not in this universe — scan_markets lists those.' Both when-to-use and when-not-to-use are covered with a named alternative.

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