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

Goes well beyond the annotations (readOnlyHint=false, openWorldHint=true, destructiveHint=false): it discloses that the server performs an outbound HTTPS GET, that redirects are rejected, a hard 20 KB cap with rejection behavior, the token/permission limitation, and the caching/scraping side effect of publishing to public repos. This is exactly the context 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?

Front-loaded with the core action in the first sentence, then constraints and warnings in descending priority. The GitHub docs link and the 'no publiques contenido sensible' aside are mildly expendable but tied to a real misuse risk, so waste is small.

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?

For an 8-parameter mutation with no output schema, the description covers mechanism, limits, failure modes and alternatives well. It never says what comes back (created artifact id? confirmation?) nor that supplying artifact_id switches to update mode, which an agent calling it blind would want.

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 only 50% and the description fully compensates for the most consequential parameter, url: it specifies raw-content semantics, allowed hosts, and no redirects, which the schema's one-line 'URL RAW del archivo' does not. Edge concern: tipo/origen/nota/document_id remain undocumented anywhere, but with url negotiation and safety fully covered and the tool's overall contract clear, this lands solidly above baseline; dropping to 4 only if one penalizes the silent optional params.

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?

Opens with a specific verb + resource + mechanism ('Guarda un artefacto que el SERVIDOR se baja de una URL'), immediately distinguishing it from the client-side upload path. It then names the exact host allowlist and contrasts against save_artifact and the Chrome extension, so an agent can tell it apart from append_artifact / save_artifact without opening schemas.

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?

Explicit when-to-use (file already published on raw.githubusercontent.com / gist / objects hosts, direct raw link without redirects), when-not (anything over 20 KB, gist writes blocked in Claude sandboxes, private repos since the server has no token), and names the concrete alternatives ('usá save_artifact', Chrome extension).

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