discord_set_application_icon

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

Annotations already declare the mutation profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=true). The description adds context annotations cannot carry: the ownership requirement that governs whether the call succeeds, and where the resulting image is surfaced. It does not describe failure/permission-error behaviour, which keeps it from 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?

Three short sentences, front-loaded with the resource and its disambiguation, then the precondition, then the input/output contract. No filler, and the most decision-relevant fact (which icon this is) comes first.

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?

A single-parameter mutation tool with an output schema, so the description need not explain return values — yet it does, and it also covers the ownership precondition and accepted input forms. Only the absence of any note on failure modes or permission errors leaves a small gap.

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 the parameter description already enumerates https URL, data URI and bare base64, plus formats and the 10 MB cap. The description restates the accepted encodings without adding constraints or examples beyond the schema, so the baseline of 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 ('Change the owning application's icon') and immediately disambiguates it from two near-neighbours in the sibling set: the bot avatar (discord_set_bot_avatar) and the server icon (discord_set_guild_icon). An agent can pick this tool without opening 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?

Gives a concrete precondition for use ('Requires the application to be owned by the token's owner') and draws the boundary against the bot-avatar and guild-icon tools by describing where each image appears (OAuth2 consent screen, developer portal). It stops short of explicit when/when-not routing language, but the context is clear.

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