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

Annotations already establish readOnlyHint, idempotentHint, non-destructive and closed-world behavior, so the safety profile is covered. The description adds value beyond that by disclosing the result shape in both modes (all names grouped by category vs. matching metrics with format and exact definition), which the agent cannot learn from annotations or the absent output schema.

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?

Three short sentences, front-loaded with the tool's purpose, then branching cleanly into no-search and search behavior. The phrase 'Look up' is repeated at the start of two consecutive sentences, a small redundancy that costs a little tightness.

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 single optional-parameter read tool with rich annotations and no output schema, the description covers purpose, both modes, and what comes back, so an agent can call it correctly. Only the relationship to sibling lookup/catalog tools is 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% and the single parameter's schema text ('Optional search text') is minimal, so the description meaningfully improves on it by giving concrete example queries ('IV rank', 'yield') and spelling out the null-vs-value behavior. This is more than the baseline 3 for a fully documented 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?

The description uses a specific verb+resource ('look up ... Qanvo's metrics ... including how each is calculated') and covers both a glossary role (defining plain words like 'quality') and a catalog role (canonical metrics available for screening). It is clearly distinct from siblings like market_query or qanvo_app_catalog, though it never names an adjacent tool to route against.

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 description explains the two invocation modes ('Without search: every metric name, grouped by category. With search (e.g. 'IV rank', 'yield'): matching metrics...'), which is useful guidance for how to call it. However, it gives no explicit when-to-use/when-not guidance relative to sibling tools, leaving the agent to infer that this is the definition-lookup tool rather than a screening or data tool.

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