postfast-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 effectively describes the multi-step process ('detects content type, gets a signed URL, uploads the file'), which goes beyond basic functionality. However, it lacks details on error handling, file size limits, or authentication requirements.

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 in the first sentence, followed by a concise breakdown of the process. Every sentence adds value without redundancy, making it efficiently structured.

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 tool with one parameter (fully documented in schema) and no output schema, the description provides good context on the upload flow and output usage. However, it could be more complete by mentioning the return format (e.g., JSON with media key and type) or potential errors.

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 input schema has 100% description coverage, with 'filePath' clearly documented as 'Absolute path to the local file'. The description adds no additional parameter semantics beyond what the schema provides, so it meets the baseline of 3.

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 specific action ('upload a local file'), the target resource ('to PostFast'), and the outcome ('get back a media key for use in create_posts'). It distinguishes itself from siblings like 'get_upload_urls' by handling the full upload flow rather than just generating URLs.

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 clear context for when to use this tool ('for use in create_posts'), but does not explicitly state when not to use it or name alternatives. For example, it doesn't contrast with 'get_upload_urls' which might be for partial upload workflows.

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