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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds substantial context beyond them: the cost lifecycle (estimated_cost is a hold, usage.cost is final after completion), the 72-hour file retention, the 25 MB resource-serving limit with an HTTP fallback endpoint, and rate-limit-style polling advice. That is exactly the kind of behavior an agent cannot infer from the schema.

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?

Front-loaded with the status meaning, then cost semantics, then file delivery mechanics, then polling cadence. Every sentence carries distinct, actionable information with no padding.

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?

Even though an output schema exists (so return values need not be described), the description proactively explains the cost fields, the video/mp4 MCP resource, and the 25 MB/HTTP fallback path. For a polling status tool, an agent has everything needed to call it and consume the result correctly.

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% and the single id parameter is already documented as 'Task id returned by video_create.' The description reinforces the origin of the id and maps it to the REST path parameter {id}, but adds no syntax or format detail beyond the schema. Baseline 3 applies when the 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?

States a specific verb and resource ('Status of a video task started with video_create') and immediately enumerates the possible states, so the agent knows exactly what is returned. It also names the sibling tool that produces the id, distinguishing it from video_create unambiguously.

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?

Gives explicit operational guidance: 'Free to call: it only reads the task. Poll every 15–30 seconds, not more often.' It also names the upstream tool (video_create) whose output is required. When-to-use and cadence are both spelled out, leaving little to inference.

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