pyfastmail-mcp

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

No annotations are provided, so the description carries full burden. It states the tool deletes an event, which implies a destructive mutation, but doesn't disclose behavioral traits like whether deletion is permanent, requires specific permissions, has side effects (e.g., on recurring events), or rate limits. The description is minimal and lacks critical context for a destructive operation.

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 action in the first sentence, followed by a brief parameter explanation. It's appropriately sized with no wasted words, though the structure is simple and could be more organized (e.g., bullet points). Every sentence adds value, making it efficient.

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?

Given the tool's complexity (destructive mutation), lack of annotations, and presence of an output schema (which handles return values), the description is incomplete. It covers the basic purpose and parameter semantics but misses behavioral transparency (e.g., safety, permissions) and detailed usage guidelines. For a delete tool, this leaves gaps in understanding risks and prerequisites.

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 0%, so the description must compensate. It adds meaning by explaining that 'href' is 'The href of the .ics resource (from calendar_list_events)', clarifying its source and format (.ics). This provides essential context beyond the schema's basic string type, though it could detail format constraints further. With one parameter, this is adequate.

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 states the action ('Delete') and resource ('CalDAV event'), and specifies the method ('by its href'). It distinguishes from siblings like calendar_update_event (modify) and calendar_get_event (retrieve), but doesn't explicitly contrast with calendar_list_events (list). The purpose is specific and 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 implies usage by stating the href should come 'from calendar_list_events', suggesting a workflow. However, it doesn't provide explicit guidance on when to use this tool versus alternatives (e.g., no mention of prerequisites like authentication or permissions) or when not to use it. The context is implied but not comprehensive.

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