Modal MCP Server

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

No annotations provided, so description carries full burden. Discloses infrastructure (Chrome + FFmpeg, Supabase) and return type (public MP4 URL). Missing critical behavioral traits: whether operation is synchronous (blocks until video ready) or asynchronous (returns job ID), error handling, URL expiration, and what 'memory' persistence actually means.

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?

Two dense sentences. First covers entire pipeline (render → upload → save → return), second covers format constraints. Zero redundancy. Information-to-word ratio is excellent; every clause earns its place.

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?

Complex tool (7 params, nested objects, video pipeline) with no annotations or output schema. Description compensates by stating return value (MP4 URL). However, for a potentially long-running video render operation, failing to specify sync/async behavior or job lifecycle leaves critical gaps in 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?

Schema has 100% coverage, establishing baseline 3. Description adds concrete value by enumerating example format IDs (instagram_reel_v1, explainer_v1, etc.) beyond schema's generic 'Format ID' definition. 'Etc.' implies extensibility. Could add guidance on sections array structure but schema handles that adequately.

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?

Clear specific action (Render Remotion composition) and resource pipeline (Modal cloud → Supabase → memory). Distinguishes from siblings modal_render_get/list through action verbs implying creation vs retrieval. 'Save job to memory' is slightly ambiguous (RAM vs persistence). Would be perfect with explicit 'creates new render job' contrast.

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?

Lists valid format enums (instagram_ugc_v1, etc.) which guides input selection. Lacks explicit when-to-use vs siblings (e.g., 'use this to create new renders, use modal_render_get to check status'). No prerequisites mentioned (e.g., valid composition ID requirements).

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