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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds meaningful context beyond annotations: it names FilingSummary.xml as the source, describes one-entry-per-Report behavior, and explains that an empty list typically means no FilingSummary.xml or no indexing yet. This is useful behavioral disclosure, though not exhaustive about return ordering or limitations.

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?

The description is front-loaded with the core action, then explains return shape, canonical types, empty-list semantics, and the single argument. Each sentence adds useful context without wasteful repetition.

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?

Given a single required parameter, rich annotations, and an output schema, the description is complete enough to call the tool correctly. It explains the source data, what entries contain, how to use the filename, example canonical roles, and what an empty result means.

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 for accession_number is 0%, so the description must compensate. It does so by defining the parameter as an SEC accession number and providing a concrete example format ('0000320193-25-000079'), which is important for correct invocation. For a single required parameter, this is adequate.

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 and resource ('List every R*.htm financial table in a filing') and clearly explains what is returned: one entry per <Report> from FilingSummary.xml. It also distinguishes itself from get_document by noting the returned filename is what you pass to that sibling, and explains the canonical xbrl_role_normalized field.

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 gives a clear use case: finding financial tables and locating statements like the income statement across filers via canonical roles. It also explains the empty-list condition, which helps an agent interpret results. It does not explicitly compare itself to list_filing_items or get_financial_statements, but the context is strong enough for a 4.

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