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: 'Changes nothing on the server,' re-callable to switch at any time, 24-hour persistence for the signed-in account on the hosted server, no auth required, and no validation errors (404 surfaces only on the first app-scoped call). This is exactly the kind of behavioral detail annotations cannot carry.

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?

The key fact (session-only, set app context) is front-loaded and every sentence carries information. It is dense and slightly run-on in the later clauses about hosted-server persistence and authMode defaulting, but nothing is wasted.

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 still covers the full picture: session vs. server scope, auth requirements, error behavior, persistence duration, and interaction with ethora-app-create and ethora-auth-mode-set. An agent has everything needed to call it 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 coverage is 100%, so the baseline is 3, but the description adds the cross-parameter interaction that the schema does not state: providing appToken defaults the auth mode to app-token unless authMode overrides, and it stores currentAppId/appToken. That interplay between the optional params is genuine added value.

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: 'Set the current app context for this session.' The opening 'Session-only: remembers which app later calls refer to' immediately distinguishes it from server-mutating siblings like ethora-app-create or ethora-app-update.

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?

Explicitly says when to use it ('so app-scoped tools can omit their appId argument') and when it is unnecessary ('ethora-app-create selects the new app by itself, and an account with exactly one app has it selected automatically'). It also names the related tool it pairs with (ethora-auth-mode-set), giving the agent clear routing.

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