pyfastmail-mcp

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states this is a deletion operation, implying it's destructive, but doesn't specify whether it's reversible, requires specific permissions, has side effects, or details error handling. This is inadequate for a mutation tool with zero annotation coverage.

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 efficiently structured with a clear purpose statement followed by parameter details. Every sentence adds value—none are redundant or wasteful—making it appropriately sized and front-loaded.

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 operation), lack of annotations, and presence of an output schema (which reduces need to describe return values), the description is minimally adequate. It covers the basic action and parameter semantics but lacks critical behavioral details like safety warnings or usage context.

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?

The description adds meaningful context for the single parameter 'href', explaining it's 'the href/URL path of the vCard resource (as returned by contacts_list)'. This clarifies its source and format beyond the schema's minimal title 'Href', compensating well for the 0% schema description coverage.

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 ('a contact from a CardDAV address book'), making the purpose immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'contacts_update_contact' or 'files_delete' beyond the resource type, missing specific sibling distinction.

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 provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., needing a contact href from 'contacts_list'), exclusions, or comparisons with other deletion tools like 'calendar_delete_event' or 'mail_delete_email'.

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