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

Annotations already cover the safety profile (readOnly=false, idempotent=false, openWorld=true, destructive=false). The description adds genuinely useful behavior beyond that: it reveals the async job pattern ('A job: songs with song_id and mp3, or a jobid for mureka_get_job') and the POST /music/extend endpoint. It does not spell out auth or rate-limit behavior, keeping it just short of a 5.

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 core action and tightly worded with zero filler, but the final telegraphic sentence ('A job: songs with song_id and mp3, or a jobid for mureka_get_job') is slightly clipped and reads awkwardly.

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 usefully states the return shape (lengthened songs carrying song_id and mp3, or a jobid) and the async follow-up path. Combined with explicit sibling routing and schema-documented params, an agent has what it needs to call the tool correctly; only auth/retry details are absent.

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 coverage is 100% and both parameters are documented in the schema, including the song_id format and the account-scoping behavior. The description adds nothing about parameter syntax or constraints beyond what the schema already provides, so the baseline 3 applies.

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 with scope: 'Continue an existing song from its end with new lyrics, returning the lengthened songs.' It also names the sibling tools that handle different tasks (mureka_edit_section, mureka_remix_song), so the agent can separate this tool from its neighbors without reading any schema.

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?

Explicit routing rules are given: use mureka_edit_section to change one part, use mureka_remix_song to re-record in a new style. This is clear when/when-not guidance with named alternatives, not merely implied context.

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