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

Annotations only declare readOnlyHint=false, openWorldHint=true, destructiveHint=false. The description adds genuine behavioral context: the URL is temporary/signed, size limits reach hundreds of megabytes, and two distinct outputs are produced (upload_url for binary upload, media_url for streaming). It does not state expiry duration or auth requirements, but adds substantial value over annotations.

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?

Three sentences, front-loaded with the operation, with no filler. The curl/python sentence is slightly wordy but earns its place by telling the agent how to actually perform the upload. No redundancy with the title or name since title is null.

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?

With no output schema, the description correctly compensates by naming both return values (upload_url and media_url) and their purpose, and it covers the size envelope. What is missing is routing guidance against upload_media_chunk, but for a single-purpose URL-generation tool it is otherwise complete enough to invoke 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%, so the schema already documents file_name, content_type, and file_size_bytes. The description only implies accepted media types (videos/audios) and adds no format or syntax detail beyond the schema. Baseline 3 applies when structured data carries the parameter burden.

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: generating a temporary signed upload URL for videos/audio. It clarifies scope (chat attachments or local sandbox workspace) and names the downstream consumer, discover_highlights. However, it never distinguishes itself from the sibling upload_media_chunk, leaving a plausible alternative unexplained.

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 implies the usage context (files up to hundreds of MB, uploaded via a one-line curl/python command) and where files may originate. But it gives no explicit when-to-use versus when-not, and no guidance on choosing between this tool and upload_media_chunk. Usage is inferred rather than stated.

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