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

Annotations already mark the tool as readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context: it is a single-call discovery operation, returns field schemas, and clarifies that directories support SAML federation and may house different user types. This goes beyond the annotations without contradicting them.

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 front-loaded with the core purpose and returns information, followed by domain context and parameter guidance. The SAML and multi-directory explanations are helpful for understanding what directories are, though slightly more verbose than strictly necessary for invoking the tool. Still, every sentence contributes value.

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 appropriately states what the tool returns: id, name, and field definitions. It also explains why the id matters, how to filter or list all, and the optional parameters are fully covered by the schema. For a read-only discovery tool with four optional parameters, the description is sufficient for correct invocation.

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 schema already documents all four parameters fully. The description adds a practical note about nameFilter (search vs. list all) and mentions the id's downstream use, but overall it does not add substantial semantic detail beyond the schema. Baseline 3 is appropriate.

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 ('Discovers') with a clear resource ('directories in the Caspio account'), and immediately distinguishes itself from sibling tools like discover_tables and discover_views by explaining that directories are identity/authentication services. It also states the primary output (id, name, field definitions) and even links to query_directory_users, making the tool's role unambiguous.

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 clear usage context: it is the tool to call for directory discovery, can return all directories or filter by name, and the returned id is needed for query_directory_users. It does not explicitly contrast with discover_tables/discover_views or state when not to use it, so it misses full exclusion guidance, but the context is strong.

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