Build a browser logo URL

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the description only needed to add beyond that, and it does: no provider call is made, nothing is downloaded, and hotlink fetching is blocked. Those are real operational facts not derivable from the annotations. It omits the return format, 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 core purpose and followed by the restriction that matters most. No filler, though the wording could be tightened slightly ('programmatic fetching these hotlinks is prohibited/blocked' is a touch redundant).

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?

The description covers what the tool produces conceptually (a URL) and its usage restriction, which is the most important context given no output schema exists. However, with 10 parameters at 50% schema coverage and no output schema, an agent gets no guidance on how the returned URL varies with format, theme, dimensions, or fallback, leaving a real gap for a multi-parameter builder.

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 only 50% across 10 parameters, so the description carries a compensation burden it does not meet: it never explains identifier vs. identifier_type, theme, width/height, format restrictions, or fallback behavior. The lone relevant phrase, 'selected profile client ID,' does not even map cleanly to any named parameter (the closest is 'account', described as a private profile label).

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?

The description states a specific action (URL construction) on a specific resource (logo assets) using the selected profile client ID, so an agent knows this builds a URL rather than returning image data. It is somewhat jargon-heavy ('Local Logo API URL') and never names the sibling it contrasts with, such as download_brand_logos, but the core verb+resource pair is unambiguous.

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?

It gives an explicit usage boundary: 'Direct browser display only; programmatic fetching these hotlinks is prohibited/blocked.' That is a genuine when/when-not constraint an agent must respect. It stops short of naming the correct alternative tool for actually retrieving logo bytes, so a 5 is not warranted.

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