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

The description goes well beyond the annotations, adding critical behavioral details: media URLs 'expire within hours - fetch promptly, never store', posts are returned 'newest-first', pagination uses 'before=<next_cursor>', and comment windows are limited. These are operational nuances that an agent needs to handle correctly, and they align with the readOnly/idempotent annotations without contradiction.

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 description is moderately long but information-dense. It front-loads the core purpose and then organizes details by channel refs, post refs, media URLs, and limitations. Every sentence contributes useful information, though it could be slightly more structured (e.g., bullet points) for easier skimming. Overall it's appropriately sized given the tool's complexity.

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 return values for both reference types, pagination, search, output formats, media expiry, and accessibility constraints. Since there is no output schema, the description effectively communicates what the agent can expect in the response. It is complete for a read-only fetch tool with rich annotations and a well-documented schema.

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?

The schema already provides 100% description coverage for all 8 parameters, so the baseline is 3. The tool description adds meaningful interaction semantics: explaining that 'before' comes from 'next_cursor', that query searches within the channel's full history, and that 'format' trades off token usage vs. structured data. This adds value beyond the schema's per-parameter descriptions.

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 clearly states the tool's function: 'Fetch a public Telegram channel or post - no account or API key involved.' It distinguishes between channel refs and post refs, and explicitly contrasts with the sibling tool glim_telegram_search by focusing on fetching specific resources rather than searching. The verb+resource pattern is specific and 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?

The description provides clear context for when to use the tool: when you have a public channel or post reference. It also gives an exclusion: 'Only channels with a public web preview work... private channels and groups are not accessible.' However, it does not explicitly mention alternative tools like glim_telegram_search for discovery use cases, so it lacks explicit when-not-to-use guidance relative to siblings.

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