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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and the description adds substantial behavior beyond that: closed platforms are marked 'no longer operating' with a count distinguishing live matches, fees/terms/descriptions are deliberately absent from results, and a hard anti-fabrication rule ('a figure you remember about a platform will be read as a figure from this catalogue'). No contradiction with annotations.

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?

A single dense paragraph front-loads the core purpose before all behavioral caveats. Every sentence earns its place: return fields, use case, exclusions with alternative, closed-platform semantics, absent-field handling, and the no-fabrication rule — no filler or repetition of schema content.

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 23-parameter, 0-required tool the description covers the meaningful edges an agent needs: what is and is not in results, closed-platform semantics, the enumeration constraint, and the citation requirement. Pagination and parameter defaults are already in the rich schema, and an output schema exists, so return value details do not need to be restated.

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% — all 23 parameters carry descriptions with enum distributions, defaults, and code examples (e.g., 'de for Germany, gb for the United Kingdom') — so the schema does the heavy lifting. The description adds only a general guardrail ('Every filter value is enumerated in this schema; do not invent one') rather than per-parameter detail, matching the baseline 3 for high coverage.

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 opens with a specific verb-resource pair ('Search the CrowdSpace catalogue of crowdfunding and P2P lending platforms') and enumerates the exact return fields. It explicitly names get_market_overview as the sibling it is not, and contrasts itself with the profile page, so an agent can disambiguate without opening other 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?

Provides explicit when-to-use ('answer which platforms let me… questions') and when-not-to-use ('Do NOT use it for a full platform profile... nor for market-wide numbers') with the named alternative get_market_overview. It also adds operational rules: always link the returned profile URL, use only enumerated filter values, and report the still-running count rather than the raw total.

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