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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the bar is lower. The description still adds real context: the call is free (cost signal) and the payload covers coverage and freshness metadata, not live records. It omits response size/pagination behavior for the all-entities case.

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 sentences: what it returns, then when to call it. Zero filler and the most decision-relevant fact ('use this first') is front-loaded.

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, the description usefully enumerates the response members (identifiers, attributes, relationships, coverage, freshness), which is the right compensation. Minor gap: it doesn't indicate that omitting entity_type returns the full multi-domain payload or how large that is.

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 schema itself explains entity_type, the include_* flags, defaults and the empty-object behavior thoroughly. The description mentions no parameters at all, so it adds nothing beyond the structured fields — baseline 3 applies.

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 ('Get') and enumerates exactly what is returned: entity types, identifiers, searchable attributes, relationships, reference domains, coverage and freshness. 'Free discovery tool' frames it as read-only metadata. It does not explicitly name the sibling it replaces (get_reference_data), so it falls short of 5.

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?

'Use this first when an agent does not know the data model or valid filters' gives explicit sequencing guidance that clearly separates it from the search/resolve siblings. It implies but never states the inverse (skip it if you already know the model), so no exclusion is spelled out.

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