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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does disclose what the operation returns (entity type definitions with their descriptor JSON schemas) and implies a read-only listing. But it does not clarify workspace scoping semantics, pagination behavior, or what happens with the built-in types by default. For a simple list tool this is adequate but not rich, warranting a 3.

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 two tight sentences with zero waste. The core purpose is front-loaded in the first sentence, and the usage directive in the second earns its place. No redundancy, no filler, and it is appropriately brief for a simple list tool.

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 and no annotations, the description compensates reasonably: it states the operation, the return content (types with descriptor JSON schemas), and gives the sequencing guidance to read it before composing custom fields. All parameters are fully documented in the schema. The only gap is not clarifying the relationship to the sibling listing tools, but for a straightforward list operation this is reasonably complete.

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 description coverage is 100%, so the baseline is 3. The description adds no parameter-level detail beyond what the schema already documents; it does not elaborate on any of the five parameters (page, pageSize, includeBuiltIn, session_id, context). Since the schema fully covers the parameters, the description neither helps nor hurts, keeping it at baseline 3.

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 ('List') and a clear resource ('entity type definitions in this workspace') and adds what each entry contains ('the JSON schema its descriptor must satisfy'). This is clear and meaningful, and conceptually separates it from listEntityDescriptors (descriptors) and getDefinition (single entity). However, it never names any sibling or explicitly differentiates itself, so it stays at a 4 rather than a 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?

The description gives a genuine usage context: 'Read this before interpreting or composing an entity's custom fields.' This tells the agent when to invoke it but does not mention alternatives, when not to use it, or how it differs from similar tools like listEntityDescriptors or getDefinition. There is context but no exclusions, landing it between a 3 and a 4; the thinness of the single directive pulls it to 3.

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