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

The description goes beyond the readOnlyHint annotation by disclosing that it reads the file system directly and always reflects the latest uncommitted state. It also clarifies configuration via header, which is useful behavioral context not present in the 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?

The description is organized and front-loaded with the most important routing information ('WHEN' and triggers), followed by the core behavior and configuration details. Every sentence serves a clear purpose and there is minimal redundancy.

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-only listing tool with one optional parameter, the description covers what it lists, how it reads data, and how to configure the path. It does not define the return format, but no output schema exists and the expected result is reasonably inferable from the tool's purpose.

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 parameter is simple, but the description adds valuable context: how the path can be set persistently via header and how the parameter overrides that configuration. This goes beyond the schema's bare parameter description.

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 clearly identifies the operation with a specific verb ('List'), a concrete resource ('all D365 F&O objects in the custom/extension model directory on disk'), and a clear distinguishing scope ('custom/extension' vs general objects). The included trigger phrases reinforce intent understanding and differentiate it from generic sibling listing tools.

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 'WHEN' clause and trigger examples give explicit context for when an agent should select this tool. It does not mention alternatives or exclusions, but the scope is narrow enough that the usage context is clear.

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