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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is low; the description still adds ordering (newest first), the returned field set, the pagination mechanism, and the underlying endpoint GET /music/characters. It does not mention rate limits or result-size caps, so 4 rather than 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?

Dense but efficient: the core list behavior and returned fields come first, then sibling routing, then pagination. Every clause carries information, though the packed sentence listing three sibling tools is slightly heavy for a single line.

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 compensates by naming the returned fields and ordering plus the pagination contract, which is what an agent needs to call and consume this tool. The optional account parameter and any handling of an empty list remain unaddressed, keeping it below a 5.

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 both parameters (account, last_id) are already documented, making 3 the baseline. The description reinforces last_id's pagination role but adds no syntax or format detail beyond the schema, and never mentions the optional account parameter.

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 ('List your characters (reusable singers)'), clarifies the domain-specific term with a gloss, and enumerates the returned fields and ordering ('newest first: name, tags, private or published...'). It is clearly distinguishable from siblings like mureka_list_voices or mureka_list_songs.

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?

Routes the agent to the adjacent operations explicitly: create via mureka_create_character, change visibility via mureka_set_character_private, and use the returned character_id with mureka_create_song_with_lyrics. It also explains how to paginate ('Pass last_id for the next page'). No explicit when-not-to-use or exclusion, so it falls short of a 5.

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