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

readOnlyHint=true already declares this is a safe non-mutating read, so the description's burden is lighter. It adds the ownership scoping (the entity belongs to a customer) and the underlying endpoint, but says nothing about not-found behavior, cross-customer access rules, or what the response contains beyond the expand hint in the schema.

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 short sentences, front-loaded with the purpose, with no padding. The trailing REST endpoint reference is mildly redundant for an agent but small enough not to hurt readability.

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 simple read tool with a fully described 3-parameter schema and readOnlyHint annotations, this is essentially sufficient. The only real gap is error/absence handling (what happens when the entity does not exist or belongs to another customer), which the absence of an output schema makes slightly more relevant.

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 all three parameters (expand, entity_id, customer_id) are already documented in the schema, which sets the baseline at 3. The description reinforces the customer/entity ownership relationship but adds no syntax, format, or selection guidance beyond the schema's own expand examples.

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 (fetch) and resource (a single entity belonging to a customer), with a concrete example (a seat) that clarifies what an entity is. The word "single" implicitly separates it from autumn_list_entities, but no sibling is named explicitly, so a tiny bit of inference is required.

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?

Usage is only implied: 'single entity' suggests it is the direct-lookup counterpart to autumn_list_entities, and the required customer_id/entity_id pair implies you must already know both IDs. There is no explicit when-to-use, when-not, or pointer to the list/attach alternatives.

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