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

Goes well beyond the annotations: it discloses that the call returns immediately with status 'starting', that readiness takes about 12 seconds (longer when packages install), that a restart terminates sessions of current users (matching destructiveHint), and that the app sleeps after the idle timeout. This is the kind of behavioral context annotations cannot convey.

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-loads the verb and the immediate-return behavior, then layers in timing, session impact, and the always-on alternative. It is dense but not wasteful, though the final sentence about cold-start waiting overlaps somewhat with the earlier idle-timeout sentence.

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 explains the return surface: immediate 'starting' status, later 'running' via fastero_get_streamlit_app, errorMessage on failure, and logs via fastero_get_streamlit_app_logs. Everything an agent needs to call it and interpret the result is present.

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 appId and projectId are already documented in the schema. The description adds no further meaning about parameter format or source beyond what the schema provides, so 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 ('Start a Streamlit app') plus the restart nuance, which cleanly separates it from fastero_stop_streamlit_app and fastero_create_streamlit_app. An agent can identify the operation without opening the 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?

Explains the core use case (bring an app up) and points to a concrete alternative for avoiding cold starts: fastero_set_streamlit_always_on. It does not state explicit when-not conditions, but the guidance is clear enough to act on.

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