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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds two useful traits beyond that: it makes no paid request (cost behavior) and does not commit to selecting an ambiguous symbol (non-resolving behavior). It still says nothing about result shape or how candidates are ranked/limited.

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 short sentences with the core purpose front-loaded and no filler. It is tight, though the terseness comes partly at the expense of the parameter and usage detail an agent would want.

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, 0% parameter description coverage, and no naming of the resolve_instrument alternative, the description leaves significant gaps. For a four-parameter lookup tool it should at least explain the filtering flags and what candidates are returned.

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 0% with four parameters (symbol, limit, cs_only, details), yet the description explains none of them. 'Across exchanges' barely gestures at search scope but does not clarify cs_only, details, or the limit cap, so it fails to compensate for the coverage gap.

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 clear verb and resource ('Search public instrument candidates across exchanges'), so the agent knows it returns candidate instruments rather than single resolved ones. It stops short of naming the obvious sibling (stocktrends_resolve_instrument), leaving the differentiation implicit rather than explicit.

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?

The clause 'does not select an ambiguous symbol' implies this tool is for candidate discovery rather than resolution, and 'does not make a paid request' hints at a free pre-step. However, it never states when to prefer this over stocktrends_resolve_instrument or other siblings, so usage is only implied.

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