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

Annotations already cover readOnly/idempotent/non-destructive, so the bar is lower, but the description adds genuinely useful behavior: it returns disclosure EVENTS (company, NIF, category, title, Madrid-time publication timestamp, registration number, document URL) rather than extracted XBRL facts, and notes publication freshness/latency versus the ESEF index. It does not discuss failure modes for unresolved nif/isin/company lookups, which is a minor gap.

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?

Information-dense and front-loaded: coverage, then preference over the alternative, then filters, then what it returns, then the handoff to cnmv_annual_reports. Long, but nearly every clause carries routing or scope information; only mild redundancy with the schema on filter parameters.

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, yet the description enumerates the returned event fields and explicitly warns that no extracted XBRL facts are included, which is exactly what an agent needs to decide fit. Aliasing of feeds, date defaults, and issuer resolution are all covered.

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 each parameter is well documented, so the baseline is 3. The description reinforces the date window (inclusive, default last 7 days) and the issuer-filter options (nif, isin or company name), but adds little semantics beyond what the schema already states in detail.

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), resource (Spanish listed-company regulated disclosures filed with CNMV) and the two disclosure categories it covers. It explicitly distinguishes itself from esef_filing_search and cnmv_annual_reports, so an agent can tell it apart from siblings 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?

Explicit routing: 'PREFER OVER esef_filing_search FOR SPANISH ISSUERS' with the reason (CNMV publishes within minutes vs. months behind for ESEF), plus 'For an issuer's annual financial reports with their ESEF ZIP download, use cnmv_annual_reports.' Both when-to-use and the alternative are named.

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