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. It discloses important behavioral traits: only returns published posts with platform IDs, excludes LinkedIn personal accounts, and lists supported platforms. However, it doesn't mention pagination behavior, rate limits, authentication requirements, or what happens with invalid parameters.

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 perfectly front-loaded with the core purpose in the first clause, followed by important constraints and supported platforms. Every sentence earns its place with zero wasted words, making it highly efficient for an AI agent to parse.

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 read operation with 4 parameters and 100% schema coverage but no output schema, the description provides good context about what's returned (posts with performance metrics) and important constraints. However, without an output schema, it should ideally describe the return format more explicitly (e.g., structure of the metrics data).

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 parameters thoroughly. The description adds some context by mentioning 'platforms' filtering and 'social media account IDs' filtering, but doesn't provide additional semantic meaning beyond what's in the schema. Baseline 3 is appropriate when schema does the heavy lifting.

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 ('Fetch'), resource ('published posts'), and specific scope ('with their latest performance metrics'). It explicitly distinguishes from siblings like 'list_posts' by specifying it returns performance metrics and only published posts with platform IDs.

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 about when to use this tool (for fetching posts with performance metrics) and includes important exclusions (LinkedIn personal accounts are excluded). However, it doesn't explicitly mention when to use alternatives like 'list_posts' or 'list_accounts' for different needs.

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