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

Annotations declare readOnlyHint=false and destructiveHint=false, so the write-but-non-destructive profile is already structured. The description adds real context beyond that: the app is created stopped, two apps may share a name, and owners/admins/editors are the roles that may create one. Return contents are described too.

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 what the tool creates, then behavior, then sibling routing; every sentence carries either a constraint or a routing decision. It is dense and long-ish for a single paragraph, but no sentence is filler.

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?

No output schema exists, and the description compensates by naming the returned fields (appId, status, viewerUrl, other settings, without files). Entrypoint constraints, permissions, and lifecycle are all covered, leaving nothing an agent needs missing.

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 and the schema already explains name, files, path and projectId. The description reinforces the app.py-at-top-level and requirements.txt constraints, but adds only one genuinely new semantic ('two apps may share a name') beyond the schema.

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 ('Create a Streamlit app in a project from the files given') and immediately defines the artifact as 'a Python web app that signed-in project members open in the browser', which separates it from notebooks and scheduled scripts. An agent can distinguish it from fastero_create_notebook and fastero_create_python_project without opening either 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?

Explicitly routes to alternatives by condition: fastero_write_streamlit_file to change one file, fastero_replace_streamlit_files to change all of them, fastero_create_notebook for in-place analysis, fastero_create_python_project for scheduled scripts. It also states the entry condition that fastero_run_streamlit_app (or a member opening the link) is what starts it, since creation leaves it stopped.

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